diff --git a/CHANGELOG b/CHANGELOG
index b5faa02..08dc3d7 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Add Object.isString, Object.isNumber, and Object.isUndefined, and clean up the source to make use of Object.isXXX where possible.  [sam]
+
 * Add the document.viewport object for querying dimensions and scroll offsets of the browser viewport.  [Andrew Dupont, Thomas Fuchs, sam]
   Example:
     document.viewport.getDimensions()     // { width: 1149, height: 923 }
diff --git a/src/ajax.js b/src/ajax.js
index 84974c4..1234768 100644
--- a/src/ajax.js
+++ b/src/ajax.js
@@ -28,10 +28,10 @@ Ajax.Responders = {
   
   dispatch: function(callback, request, transport, json) {
     this.each(function(responder) {
-      if (typeof responder[callback] == 'function') {
+      if (Object.isFunction(responder[callback])) {
         try {
           responder[callback].apply(responder, [request, transport, json]);
-        } catch (e) {}
+        } catch (e) { }
       }
     });
   }
@@ -48,7 +48,7 @@ Ajax.Responders.register({
   }
 });
 
-Ajax.Base = function() {};
+Ajax.Base = function() { };
 Ajax.Base.prototype = {
   setOptions: function(options) {
     this.options = {
@@ -60,10 +60,10 @@ Ajax.Base.prototype = {
       evalJSON:     true,
       evalJS:       true
     };
-    Object.extend(this.options, options || {});
+    Object.extend(this.options, options || { });
     
     this.options.method = this.options.method.toLowerCase();
-    if (typeof this.options.parameters == 'string') 
+    if (Object.isString(this.options.parameters)) 
       this.options.parameters = this.options.parameters.toQueryParams();
   }
 };
@@ -158,7 +158,7 @@ Ajax.Request.prototype = Object.extend(new Ajax.Base(), {
     if (typeof this.options.requestHeaders == 'object') {
       var extras = this.options.requestHeaders;
 
-      if (typeof extras.push == 'function')
+      if (Object.isFunction(extras.push))
         for (var i = 0, length = extras.length; i < length; i += 2) 
           headers[extras[i]] = extras[i+1];
       else
@@ -332,8 +332,8 @@ Object.extend(Object.extend(Ajax.Updater.prototype, Ajax.Request.prototype), {
     
     if (receiver = $(receiver)) {
       if (options.insertion) {
-        if (typeof options.insertion == 'string') {
-          var insertion = {}; insertion[options.insertion] = responseText;
+        if (Object.isString(options.insertion)) {
+          var insertion = { }; insertion[options.insertion] = responseText;
           receiver.insert(insertion);
         }
         else options.insertion(receiver, responseText);
@@ -356,7 +356,7 @@ Ajax.PeriodicalUpdater.prototype = Object.extend(new Ajax.Base(), {
     this.frequency = (this.options.frequency || 2);
     this.decay = (this.options.decay || 1);
     
-    this.updater = {};
+    this.updater = { };
     this.container = container;
     this.url = url;
 
diff --git a/src/array.js b/src/array.js
index b38abee..89b6831 100644
--- a/src/array.js
+++ b/src/array.js
@@ -12,8 +12,8 @@ function $A(iterable) {
 if (Prototype.Browser.WebKit) {
   function $A(iterable) {
     if (!iterable) return [];
-    if (!(typeof iterable == 'function' && iterable == '[object NodeList]') && 
-      iterable.toArray) {
+    if (!(Object.isFunction(iterable) && iterable == '[object NodeList]') && 
+        iterable.toArray) {
       return iterable.toArray();
     } else {
       var results = [];
@@ -114,7 +114,7 @@ Object.extend(Array.prototype, {
 });
 
 // use native browser JS 1.6 implementation if available
-if (typeof Array.prototype.forEach == 'function')
+if (Object.isFunction(Array.prototype.forEach))
   Array.prototype._each = Array.prototype.forEach;
 
 if (!Array.prototype.indexOf) Array.prototype.indexOf = function(item, i) {
diff --git a/src/base.js b/src/base.js
index e3a37c9..07ac8d9 100644
--- a/src/base.js
+++ b/src/base.js
@@ -1,7 +1,7 @@
 /* Based on Alex Arnell's inheritance implementation. */
 var Class = {
   create: function(parent, methods) {
-    if (arguments.length == 1 && typeof parent !== 'function')
+    if (arguments.length == 1 && !Object.isFunction(parent))
       methods = parent, parent = null;
       
     var method = function() {
@@ -137,6 +137,18 @@ Object.extend(Object, {
   
   isFunction: function(object) {
     return typeof object == "function";
+  },
+  
+  isString: function(object) {
+    return typeof object == "string";
+  },
+  
+  isNumber: function(object) {
+    return typeof object == "number";
+  },
+  
+  isUndefined: function(object) {
+    return typeof object == "undefined";
   }
 });
 
@@ -212,7 +224,7 @@ var Try = {
       try {
         returnValue = lambda();
         break;
-      } catch (e) {}
+      } catch (e) { }
     }
 
     return returnValue;
diff --git a/src/deprecated.js b/src/deprecated.js
index e284025..b669303 100644
--- a/src/deprecated.js
+++ b/src/deprecated.js
@@ -106,7 +106,7 @@ var Position = {
   page: Element.Methods.viewportOffset,
 
   clone: function(source, target, options) {
-    options = options || {};
+    options = options || { };
     return Element.clonePosition(target, source, options);
   }
 };
diff --git a/src/dom.js b/src/dom.js
index 0ab6b7a..deeab3b 100644
--- a/src/dom.js
+++ b/src/dom.js
@@ -4,7 +4,7 @@ function $(element) {
       elements.push($(arguments[i]));
     return elements;
   }
-  if (typeof element == 'string')
+  if (Object.isString(element))
     element = document.getElementById(element);
   return Element.extend(element);
 }
@@ -113,7 +113,7 @@ Element.Methods = {
   insert: function(element, insertions) {
     element = $(element);
     
-    if (typeof insertions == 'string' || typeof insertions == 'number' ||
+    if (Object.isString(insertions) || Object.isNumber(insertions) ||
         Object.isElement(insertions) || (insertions && (insertions.toElement || insertions.toHTML)))
           insertions = {bottom:insertions};
     
@@ -146,7 +146,7 @@ Element.Methods = {
     element = $(element);
     if (Object.isElement(wrapper))
       $(wrapper).writeAttribute(attributes || { });
-    else if (typeof wrapper == 'string') wrapper = new Element(wrapper, attributes);
+    else if (Object.isString(wrapper)) wrapper = new Element(wrapper, attributes);
     else wrapper = new Element('div', wrapper);
     if (element.parentNode)
       element.parentNode.replaceChild(wrapper, element);
@@ -209,7 +209,7 @@ Element.Methods = {
   },
   
   match: function(element, selector) {
-    if (typeof selector == 'string')
+    if (Object.isString(selector))
       selector = new Selector(selector);
     return selector.match($(element));
   },
@@ -383,7 +383,7 @@ Element.Methods = {
   setStyle: function(element, styles) {
     element = $(element);
     var elementStyle = element.style, match;
-    if (typeof styles === 'string') {
+    if (Object.isString(styles)) {
       element.style.cssText += ';' + styles;
       return styles.include('opacity') ?
         element.setOpacity(styles.match(/opacity:\s*(\d?\.?\d*)/)[1]) : element;
@@ -680,9 +680,9 @@ if (!document.createRange || Prototype.Browser.Opera) {
   Element.Methods.insert = function(element, insertions) {
     element = $(element);
 
-    if (typeof insertions == 'string' || typeof insertions == 'number' ||
+    if (Object.isString(insertions) || Object.isNumber(insertions) ||
         Object.isElement(insertions) || (insertions && (insertions.toElement || insertions.toHTML)))
-          insertions = {bottom:insertions};
+          insertions = { bottom: insertions };
     
     var t = Element._insertionTranslations, content, position, pos, tagName;
     
@@ -1056,7 +1056,7 @@ Element.extend = (function() {
     
     for (property in methods) {
       value = methods[property];
-      if (typeof value == 'function' && !(property in element))
+      if (Object.isFunction(value) && !(property in element))
         element[property] = value.methodize();
     }
     
@@ -1118,7 +1118,7 @@ Element.addMethods = function(methods) {
     onlyIfAbsent = onlyIfAbsent || false;
     for (var property in methods) {
       var value = methods[property];
-      if (typeof value != 'function') continue;
+      if (!Object.isFunction(value)) continue;
       if (!onlyIfAbsent || !(property in destination))
         destination[property] = value.methodize();
     }
@@ -1157,7 +1157,7 @@ Element.addMethods = function(methods) {
   if (F.SpecificElementExtensions) {
     for (var tag in Element.Methods.ByTag) {
       var klass = findDOMClass(tag);
-      if (typeof klass == "undefined") continue;
+      if (Object.isUndefined(klass)) continue;
       copy(T[tag], klass.prototype);
     }
   }  
@@ -1171,8 +1171,8 @@ Element.addMethods = function(methods) {
 
 document.viewport = {
   getDimensions: function() {
-    var dimensions = {};
-    $w('width height').each( function(d) {
+    var dimensions = { };
+    $w('width height').each(function(d) {
       var D = d.capitalize();
       dimensions[d] = self['inner' + D] || 
        (document.documentElement['client' + D] || document.body['client' + D]);
diff --git a/src/enumerable.js b/src/enumerable.js
index e4e9936..2b2ae06 100644
--- a/src/enumerable.js
+++ b/src/enumerable.js
@@ -1,4 +1,4 @@
-var $break = {};
+var $break = { };
 
 var Enumerable = {
   each: function(iterator, context) {
@@ -77,7 +77,7 @@ var Enumerable = {
     iterator = iterator ? iterator.bind(context) : Prototype.K;
     var results = [];
 
-    if (typeof filter == "string")
+    if (Object.isString(filter))
       filter = new RegExp(filter);
       
     this.each(function(value, index) {
@@ -88,7 +88,7 @@ var Enumerable = {
   },
   
   include: function(object) {
-    if (typeof this.indexOf == 'function')
+    if (Object.isFunction(this.indexOf))
       return this.indexOf(object) != -1;
 
     var found = false;
@@ -190,7 +190,7 @@ var Enumerable = {
   
   zip: function() {
     var iterator = Prototype.K, args = $A(arguments);
-    if (typeof args.last() == 'function')
+    if (Object.isFunction(args.last()))
       iterator = args.pop();
 
     var collections = [this].concat(args).map($A);
diff --git a/src/event.js b/src/event.js
index 22fdbc6..cb13b3d 100644
--- a/src/event.js
+++ b/src/event.js
@@ -220,7 +220,7 @@ Object.extend(Event, (function() {
       }
 
       event.eventName = eventName;
-      event.memo = memo || {};
+      event.memo = memo || { };
 
       if (document.createEvent) {
         element.dispatchEvent(event);
diff --git a/src/form.js b/src/form.js
index 6040e34..6083548 100644
--- a/src/form.js
+++ b/src/form.js
@@ -9,7 +9,7 @@ var Form = {
     else if (options.hash === undefined) options.hash = true;
     var key, value, submitted = false, submit = options.submit;
     
-    var data = elements.inject({}, function(result, element) {
+    var data = elements.inject({ }, function(result, element) {
       if (!element.disabled && element.name) {
         key = element.name; value = $(element).getValue();
         if (value != null && (element.type != 'submit' || (!submitted &&
@@ -92,14 +92,14 @@ Form.Methods = {
   },
   
   request: function(form, options) {
-    form = $(form), options = Object.clone(options || {});
+    form = $(form), options = Object.clone(options || { });
 
     var params = options.parameters, action = form.readAttribute('action') || '';
     if (action.blank()) action = window.location.href;
     options.parameters = form.serialize(true);
     
     if (params) {
-      if (typeof params == 'string') params = params.toQueryParams();
+      if (Object.isString(params)) params = params.toQueryParams();
       Object.extend(options.parameters, params);
     }
     
@@ -130,7 +130,7 @@ Form.Element.Methods = {
     if (!element.disabled && element.name) {
       var value = element.getValue();
       if (value != undefined) {
-        var pair = {};
+        var pair = { };
         pair[element.name] = value;
         return Hash.toQueryString(pair);
       }
@@ -167,7 +167,7 @@ Form.Element.Methods = {
       if (element.select && (element.tagName.toLowerCase() != 'input' ||
           !['button', 'reset', 'submit'].include(element.type)))
         element.select();
-    } catch (e) {}
+    } catch (e) { }
     return element;
   },
   
@@ -257,7 +257,7 @@ Form.Element.Serializers = {
 
 /*--------------------------------------------------------------------------*/
 
-Abstract.TimedObserver = function() {};
+Abstract.TimedObserver = function() { };
 Abstract.TimedObserver.prototype = {
   initialize: function(element, frequency, callback) {
     this.frequency = frequency;
@@ -274,7 +274,7 @@ Abstract.TimedObserver.prototype = {
   
   onTimerEvent: function() {
     var value = this.getValue();
-    var changed = ('string' == typeof this.lastValue && 'string' == typeof value
+    var changed = (Object.isString(this.lastValue) && Object.isString(value)
       ? this.lastValue != value : String(this.lastValue) != String(value));
     if (changed) {
       this.callback(this.element, value);
@@ -299,7 +299,7 @@ Form.Observer.prototype = Object.extend(new Abstract.TimedObserver(), {
 
 /*--------------------------------------------------------------------------*/
 
-Abstract.EventObserver = function() {};
+Abstract.EventObserver = function() { };
 Abstract.EventObserver.prototype = {
   initialize: function(element, callback) {
     this.element  = $(element);
diff --git a/src/hash.js b/src/hash.js
index 963c3f6..2046a89 100644
--- a/src/hash.js
+++ b/src/hash.js
@@ -1,6 +1,6 @@
 var Hash = function(object) {
   if (object instanceof Hash) this.merge(object);
-  else Object.extend(this, object || {});
+  else Object.extend(this, object || { });
 };
 
 Object.extend(Hash, {
diff --git a/src/selector.js b/src/selector.js
index f5ca759..cdd922f 100644
--- a/src/selector.js
+++ b/src/selector.js
@@ -19,8 +19,10 @@ Selector.prototype = {
         c = Selector.criteria, le, p, m;
 
     if (Selector._cache[e]) {
-      this.matcher = Selector._cache[e]; return;
+      this.matcher = Selector._cache[e]; 
+      return;
     }
+    
     this.matcher = ["this.matcher = function(root) {", 
                     "var r = root, h = Selector.handlers, c = false, n;"];
 
@@ -29,7 +31,7 @@ Selector.prototype = {
       for (var i in ps) {
         p = ps[i];
         if (m = e.match(p)) {
-          this.matcher.push(typeof c[i] == 'function' ? c[i](m) :
+          this.matcher.push(Object.isFunction(c[i]) ? c[i](m) :
     	      new Template(c[i]).evaluate(m));
           e = e.replace(m[0], '');
           break;
@@ -55,7 +57,7 @@ Selector.prototype = {
       le = e;
       for (var i in ps) {
         if (m = e.match(ps[i])) {
-          this.matcher.push(typeof x[i] == 'function' ? x[i](m) : 
+          this.matcher.push(Object.isFunction(x[i]) ? x[i](m) : 
             new Template(x[i]).evaluate(m));
           e = e.replace(m[0], '');
           break;
@@ -119,7 +121,7 @@ Selector.prototype = {
 };
 
 Object.extend(Selector, {
-  _cache: {},
+  _cache: { },
   
   xpath: {
     descendant:   "//*",
@@ -141,7 +143,7 @@ Object.extend(Selector, {
     pseudo: function(m) {
       var h = Selector.xpath.pseudos[m[1]];
       if (!h) return '';
-      if (typeof h === 'function') return h(m);
+      if (Object.isFunction(h)) return h(m);
       return new Template(Selector.xpath.pseudos[m[1]]).evaluate(m);
     },
     operators: {
@@ -170,7 +172,7 @@ Object.extend(Selector, {
           le = e;
           for (var i in p) {
             if (m = e.match(p[i])) {
-              v = typeof x[i] == 'function' ? x[i](m) : new Template(x[i]).evaluate(m);
+              v = Object.isFunction(x[i]) ? x[i](m) : new Template(x[i]).evaluate(m);
               exclusion.push("(" + v.substring(1, v.length - 1) + ")");
               e = e.replace(m[0], '');
               break;
@@ -604,7 +606,7 @@ Object.extend(Selector, {
   },
   
   findElement: function(elements, expression, index) {
-    if (typeof expression == 'number') { 
+    if (Object.isNumber(expression)) { 
       index = expression; expression = false;
     }
     return Selector.matchElements(elements, expression || '*')[index || 0];
diff --git a/src/string.js b/src/string.js
index a1f6607..4dfb583 100644
--- a/src/string.js
+++ b/src/string.js
@@ -91,9 +91,9 @@ Object.extend(String.prototype, {
   
   toQueryParams: function(separator) {
     var match = this.strip().match(/([^?#]*)(#.*)?$/);
-    if (!match) return {};
+    if (!match) return { };
     
-    return match[1].split(separator || '&').inject({}, function(hash, pair) {
+    return match[1].split(separator || '&').inject({ }, function(hash, pair) {
       if ((pair = pair.split('='))[0]) {
         var key = decodeURIComponent(pair.shift());
         var value = pair.length > 1 ? pair.join('=') : pair[0];
@@ -216,7 +216,7 @@ if (Prototype.Browser.WebKit || Prototype.Browser.IE) Object.extend(String.proto
 });
 
 String.prototype.gsub.prepareReplacement = function(replacement) {
-  if (typeof replacement == 'function') return replacement;
+  if (Object.isFunction(replacement)) return replacement;
   var template = new Template(replacement);
   return function(match) { return template.evaluate(match) };
 };
@@ -239,7 +239,7 @@ Template.prototype = {
   },
   
   evaluate: function(object) {
-    if (typeof object.toTemplateReplacements == 'function')
+    if (Object.isFunction(object.toTemplateReplacements))
       object = object.toTemplateReplacements();
 
     return this.template.gsub(this.pattern, function(match) {
diff --git a/test/unit/base.html b/test/unit/base.html
index a0b13c8..49123ff 100644
--- a/test/unit/base.html
+++ b/test/unit/base.html
@@ -241,6 +241,38 @@
       assert(!Object.isFunction(undefined));
     }},
     
+    testObjectIsString: function() { with(this) {
+      assert(!Object.isString(function() { }));
+      assert(Object.isString("a string"));
+      assert(!Object.isString(0));
+      assert(!Object.isString([]));
+      assert(!Object.isString({}));
+      assert(!Object.isString(false));
+      assert(!Object.isString(undefined));
+    }},
+    
+    testObjectIsNumber: function() { with(this) {
+      assert(Object.isNumber(0));
+      assert(Object.isNumber(1.0));
+      assert(!Object.isNumber(function() { }));
+      assert(!Object.isNumber("a string"));
+      assert(!Object.isNumber([]));
+      assert(!Object.isNumber({}));
+      assert(!Object.isNumber(false));
+      assert(!Object.isNumber(undefined));
+    }},
+    
+    testObjectIsUndefined: function() { with(this) {
+      assert(Object.isUndefined(undefined));
+      assert(!Object.isUndefined(null));
+      assert(!Object.isUndefined(false));
+      assert(!Object.isUndefined(0));
+      assert(!Object.isUndefined(""));
+      assert(!Object.isUndefined(function() { }));
+      assert(!Object.isUndefined([]));
+      assert(!Object.isUndefined({}));
+    }},
+    
     // sanity check
     testDoesntExtendObjectPrototype: function() {with(this) {
       // for-in is supported with objects