Patched version of stickyFloat.js, a smart sticky floating box jQuery plugin

stickyFloat.js

/*
 * stickyfloat - jQuery plugin for verticaly floating anything in a constrained area
 * 
 * Example: jQuery('#menu').stickyfloat({duration: 400});
 * parameters:
 * 		duration 	- the duration of the animation
 *		startOffset - the amount of scroll offset after it the animations kicks in
 *		offsetY		- the offset from the top when the object is animated
 *		lockBottom	- 'true' by default, set to false if you don't want your floating box to stop at parent's bottom
 * $Version: 05.16.2009 r1
 * Copyright (c) 2009 Yair Even-Or
 * vsync.design@gmail.com

 * Mods by: Christopher Haupt, Webvanta Inc. 
 * http://www.webvanta.com/, http://twitter.com/chaupt, http://github.com/chaupt
 * Honor options set by user.
 */
  $.fn.stickyfloat = function(options, lockBottom) {
          var $obj        = this;
          var parentPaddingTop  = parseInt($obj.parent().css('padding-top'));
          var startOffset     = $obj.parent().offset().top;
          var opts        = $.extend({ startOffset: startOffset, offsetY: parentPaddingTop, duration: 200, lockBottom:false }, options);

          $obj.css({ position: 'absolute' });

          if(opts.lockBottom){
            var bottomPos = $obj.parent().height() - $obj.height() + opts.offsetY; //get the maximum scrollTop value
            if( bottomPos < 0 )
              bottomPos = 0;
          }

          $(window).scroll(function () { 
            $obj.stop(); // stop all calculations on scroll event

            var pastStartOffset     = $(document).scrollTop() > opts.startOffset; // check if the window was scrolled down more than the start offset declared.
            var objFartherThanTopPos  = $obj.offset().top > opts.startOffset; // check if the object is at it's top position (starting point)
            var objBiggerThanWindow   = $obj.outerHeight() < $(window).height();  // if the window size is smaller than the Obj size, then do not animate.

            // if window scrolled down more than startOffset OR obj position is greater than
            // the top position possible (+ offsetY) AND window size must be bigger than Obj size
            if( (pastStartOffset || objFartherThanTopPos) && objBiggerThanWindow ){ 
              var newpos = ($(document).scrollTop() - opts.startOffset + opts.offsetY );
              if ( newpos > bottomPos )
                newpos = bottomPos;
              if ( $(document).scrollTop() < opts.startOffset ) // if window scrolled < starting offset, then reset Obj position (opts.offsetY);
                newpos = opts.offsetY;

              $obj.animate({ top: newpos }, opts.duration );
            }
          });
        };

I am the author of this plugin, and I recently changed much of the code, to fix many things and refactor stuff.

http://dropthebit.com/74/sticky-floating-box/