$.keepAlive = {
    options: {
        url: "myScript.php",
        delay: 60*5 //5 minuten (Angabe in Sekunden!)
    }, 
 
    dummyfn:  function(){ },
   
    timeoutobj:  {
        id: -1
    },
   
    set: function(options, ondummyfn) {
        if (this.timeoutobj.id> -1)
            clearTimeout(this.timeoutobj);
   
        if (options)
            $.extend(this.options, options);
   
        if (ondummyfn)
            this.dummyfn = ondummyfn;
   
        this.timeoutobj.id = setTimeout(function() {
            $.keepAlive.beat();
        }, this.options.delay*1000);
    },
   
    beat: function() {
        $.post(this.options.url, { });
        this.timeoutobj.id = setTimeout(function(){
            $.keepAlive.beat();
        }, this.options.delay*1000);
        this.dummyfn();
    }
};