var how_many_ads = 3;
var now = new Date()
var sec = now.getSeconds()
var ad = sec % how_many_ads;
ad +=1;

if (ad==1) {
url="http://www.smartbarchicago.com/calendar/";
alt="smartbar chicago benoit and sergio";
banner="http://www.5chicago.com/themes/campaigns-december2011/sb-dec2011.jpg";
width="728";
height="90";
}
if (ad==2) {
url="http://www.hydratechicago.com/";
alt="hydrate";
banner="http://www.5chicago.com/themes/campaigns-july2011/UH-webbanner.jpg";
width="728";
height="90";
}
if (ad==3) {
url="http://www.fusicology.com/";
alt="fusicology - get in the know";
banner="http://www.5chicago.com/themes/campaigns-march2011/fusicology-728x90.jpg";
width="728";
height="90";
}

document.write('<center>');
document.write('<a href=\"' + url + '\" target=\"_top\">');
document.write('<img src=\"' + banner + '\" width=')
document.write(width + ' height=' + height + ' ');
document.write('alt=\"' + alt + '\" border=\"0\"></a><br>');
document.write('</center>');