@@ -40,6 +40,8 @@ function Browser(window, document, body, XHR, $log) {
       rawDocument = document[0],
       location = window.location,
       setTimeout = window.setTimeout,
+      clearTimeout = window.clearTimeout,
+      pendingDeferIds = {},
       lastLocationUrl;
 
   self.isMock = false;
@@ -163,15 +165,12 @@ function Browser(window, document, body, XHR, $log) {
    * @returns {function()} the added function
    */
   self.addPollFn = function(fn) {
-    if (!pollTimeout) startPoller(100, setTimeout);
+    if (isUndefined(pollTimeout)) startPoller(100, setTimeout);
     pollFns.push(fn);
     return fn;
   };
 
   /**
-   * @name angular.service.$browser#startPoller
-   * @methodOf angular.service.$browser
-   *
    * @param {number} interval How often should browser call poll functions (ms)
    * @param {function()} setTimeout Reference to a real or fake `setTimeout` function.
    *
@@ -339,20 +338,49 @@ function Browser(window, document, body, XHR, $log) {
    * @methodOf angular.service.$browser
    * @param {function()} fn A function, who's execution should be defered.
    * @param {number=} [delay=0] of milliseconds to defer the function execution.
+   * @returns {*} DeferId that can be used to cancel the task via `$browser.defer.cancel()`.
    *
    * @description
    * Executes a fn asynchroniously via `setTimeout(fn, delay)`.
    *
    * Unlike when calling `setTimeout` directly, in test this function is mocked and instead of using
-   * `setTimeout` in tests, the fns are queued in an array, which can be programmatically flushed via
-   * `$browser.defer.flush()`.
+   * `setTimeout` in tests, the fns are queued in an array, which can be programmatically flushed
+   * via `$browser.defer.flush()`.
    *
    */
   self.defer = function(fn, delay) {
+    var timeoutId;
     outstandingRequestCount++;
-    setTimeout(function() { completeOutstandingRequest(fn); }, delay || 0);
+    timeoutId = setTimeout(function() {
+      delete pendingDeferIds[timeoutId];
+      completeOutstandingRequest(fn);
+    }, delay || 0);
+    pendingDeferIds[timeoutId] = true;
+    return timeoutId;
   };
 
+
+  /**
+   * @workInProgress
+   * @ngdoc method
+   * @name angular.service.$browser.defer#cancel
+   * @methodOf angular.service.$browser.defer
+   * @returns {boolean} Returns `true` if the task hasn't executed yet and was successfuly canceled.
+   *
+   * @description
+   * Cancels a defered task identified with `deferId`.
+   */
+
+  self.defer.cancel = function(deferId) {
+    if (pendingDeferIds[deferId]) {
+      delete pendingDeferIds[deferId];
+      clearTimeout(deferId);
+      completeOutstandingRequest(noop);
+      return true;
+    }
+  };
+
+
   //////////////////////////////////////////////////////////////
   // Misc API
   //////////////////////////////////////////////////////////////
 
@@ -281,15 +281,32 @@ function MockBrowser() {
   self.cookieHash = {};
   self.lastCookieHash = {};
   self.deferredFns = [];
+  self.deferredNextId = 0;
 
   self.defer = function(fn, delay) {
     delay = delay || 0;
-    self.deferredFns.push({time:(self.defer.now + delay), fn:fn});
+    self.deferredFns.push({time:(self.defer.now + delay), fn:fn, id: self.deferredNextId});
     self.deferredFns.sort(function(a,b){ return a.time - b.time;});
+    return self.deferredNextId++;
   };
 
+
   self.defer.now = 0;
 
+
+  self.defer.cancel = function(deferId) {
+    var fnIndex;
+
+    forEach(self.deferredFns, function(fn, index) {
+      if (fn.id === deferId) fnIndex = index;
+    });
+
+    if (fnIndex) {
+      self.deferredFns.splice(fnIndex, 1);
+    }
+  }
+
+
   self.defer.flush = function(delay) {
     if (angular.isDefined(delay)) {
       self.defer.now += delay;
 
@@ -5,8 +5,11 @@ describe('browser', function(){
   var browser, fakeWindow, xhr, logs, scripts, removedScripts, setTimeoutQueue;
 
   function fakeSetTimeout(fn) {
-    setTimeoutQueue.push(fn);
-    return Math.random();
+    return setTimeoutQueue.push(fn) - 1; //return position in the queue
+  }
+
+  function fakeClearTimeout(deferId) {
+    setTimeoutQueue[deferId] = noop; //replace fn with noop to preserve other deferId indexes
   }
 
   fakeSetTimeout.flush = function() {
@@ -25,7 +28,8 @@ describe('browser', function(){
     xhr = null;
     fakeWindow = {
       location: {href:"http://server"},
-      setTimeout: fakeSetTimeout
+      setTimeout: fakeSetTimeout,
+      clearTimeout: fakeClearTimeout
     };
 
     var fakeBody = [{appendChild: function(node){scripts.push(node);},
@@ -161,6 +165,32 @@ describe('browser', function(){
       fakeSetTimeout.flush();
       expect(callback).toHaveBeenCalled();
     });
+
+
+    it('should return unique deferId', function() {
+      var deferId1 = browser.defer(noop),
+          deferId2 = browser.defer(noop);
+
+      expect(deferId1).toBeDefined();
+      expect(deferId2).toBeDefined();
+      expect(deferId1).not.toEqual(deferId2);
+    })
+
+
+    describe('cancel', function() {
+      it('should allow tasks to be canceled with returned deferId', function() {
+        var log = [],
+            deferId1 = browser.defer(function() { log.push('cancel me') }),
+            deferId2 = browser.defer(function() { log.push('ok') }),
+            deferId3 = browser.defer(function() { log.push('cancel me, now!') });
+
+        expect(log).toEqual([]);
+        browser.defer.cancel(deferId1);
+        browser.defer.cancel(deferId3);
+        fakeSetTimeout.flush();
+        expect(log).toEqual(['ok']);
+      });
+    });
   });