A greasemonkey script to add queue buttons to Hulu's "Watch [...] online" pages. Click the "raw" link to install (if you have greasemonkey).

HuluQueueButtons.user.js

// ==UserScript==
// @name        HuluQueueButtons
// @namespace   rampion.github.com
// @description Add buttons to Hulu's "Watch [...] online" pages to let you queue/dequeue videos
// @include     http://www.hulu.com/watch/*
// @version     1
// @grant       none
// ==/UserScript==

$(function(){
  // make our queue/dequeue button mimic the style of the native queue/dequeue
  // buttons we see in other pages
  $('<style>').
    html(
      '.queue-button {'+
      '  background: url("http://static.huluim.com/huluguru/masthead-s9e77b704d9.png") no-repeat scroll 0 0 transparent;'+
      '  height: 21px;'+
      '  width: 76px;'+
      '}'+
      '.queue-button {'+
      '  background-position: 0 -523px !important;'+
      '}'+
      '.queue-button:hover {'+
      '  background-position: 0 -319px !important;'+
      '}'+
      '.queue-button.added {'+
      '  background-position: 0 -384px !important;'+
      '}'+
      '.queue-button.added:hover {'+
      '  background-position: 0 -384px !important;'+
      '}'
    ).
    appendTo(document.head)
  ;
  // find the id of this video
  var id = +(document.location.toString().match(/\d+/)[0]);
  // see whether this video is already in the queue
  $.get('http://www.hulu.com/api/2.0/queued_video_ids', function(data){
    if (data.indexOf(id) >= 0){
      // and make the UI reflect this
      $queueButton.addClass('added');
    }
  });
  (function(t){
    // wait for the functional bar to be loaded into the page
    var $functionalBar = $('.functional-bar');
    if ($functionalBar.length == 0){
     setTimeout( arguments.callee, t, [2*t] ); // retry after a(n exponentially growing) delay
    } else {
      // then add our queue/dequeue button
      var $queueButton = $('<a class="beacon beacon-click queue-button"/>').
        appendTo( $functionalBar ).
        click(function(){
          // add or remove to queue, as appropriate
          $.post(
            $queueButton.hasClass('added') ? 
              'http://www.hulu.com/api/2.0/remove_from_queue' : 
              'http://www.hulu.com/api/2.0/add_to_queue',
            { id: id }, 
            function(data){
              // after add/remove, update UI
              $queueButton.toggleClass('added');
            }
          );
        })
      ;
    }
  })(1);
});