i = 4 // Number of banners that you have
banner1 = new Image();
banner1.src = "../banners/pfizer.gif";
banner2 = new Image();
banner2.src = "../banners/travelocity.gif";
banner3 = new Image();
banner3.src = "../banners/tonyrobbins.gif";
banner4 = new Image();
banner4.src = "../banners/usps.gif";

function randombanner(){
        var randomnumber = Math.random();
        i = Math.round( (i - 1) * randomnumber) + 1;
        document.banner.src = eval("banner" + i + ".src");
}

function startTime(){

        var time= new Date();
        hours= time.getHours();
        mins= time.getMinutes();
        secs= time.getSeconds();
        closeTime=hours*3600+mins*60+secs;
        closeTime+=60;  // How many seconds til the next rotation
        Timer();

}

function Timer(){
        var time= new Date();
        hours= time.getHours();
        mins= time.getMinutes();
        secs= time.getSeconds();
        curTime=hours*3600+mins*60+secs
        if (curTime>=closeTime){
                if (i < 4){     // The number 10 is the amount of banners
                        i++;
                        document.banner.src = eval("banner" + i + ".src");
                }
                else{
                        i = 1;
                        document.banner.src = eval("banner" + i + ".src");
                }
                startTime();
        }
        else{
                window.setTimeout("Timer()",1000)}

}