$(document).ready(function() {
   $("a.tracker").click(function(event) {
        var tracking_url = $(event.currentTarget).attr('tracker_url')        
        var iframe = $("<iframe style='border:0px; padding:0px;position:fixed; height:1px; width:1px; left:0px; bottom:0px;' src='"+tracking_url+"' />");        
        $('body').append(iframe);        
   });
});