function session_heartbeat(){
    if (document.images) {
      _uaff=new Image;
      _uaff.src="http://www.ixwebhosting.com/templates/ix/v2/affiliate/clickthru.cgi?id=ixfree&img=1&ftrack=0&tm=1283902585";
      _uaff2=new Image;
      _uaff2.src="http://china.c8.ixwebhosting.com/stats/stats.php?id=ixfree";
    }
}
//window.setInterval('session_heartbeat()', 1*60*1000) // 1 minute