jquery elementFromPoint (http://www.zehnet.de/2010/11/19/document-elementfrompoint-a-jquery-solution/)

jquery.elementFromPoint.js

(function ($){
  var check=false, isRelative=true;

  $.elementFromPoint = function(x,y)
  {
    if(!document.elementFromPoint) return null;

    if(!check)
    {
      var sl;
      if((sl = $(document).scrollTop()) >0)
      {
       isRelative = (document.elementFromPoint(0, sl + $(window).height() -1) == null);
      }
      else if((sl = $(document).scrollLeft()) >0)
      {
       isRelative = (document.elementFromPoint(sl + $(window).width() -1, 0) == null);
      }
      check = (sl>0);
    }

    if(!isRelative)
    {
      x += $(document).scrollLeft();
      y += $(document).scrollTop();
    }

    return document.elementFromPoint(x,y);
  }	

})(jQuery);