var how_many_ads = 3; // change this depending on the number of banners
var now = new Date()
var sec = now.getSeconds()
var ad = sec % how_many_ads;
ad +=1;

if (ad==1) {
url="http://www.shareasale.com/r.cfm?b=31525&u=94808&m=7127&urllink=&afftrack=zimpy";
banner="http://www.shareasale.com/image/468x60_blue.gif";
alt="Visit SpreadShirt.com!";
}
if (ad==2) {
url="http://www.shareasale.com/r.cfm?b=31526&u=94808&m=7127&urllink=&afftrack=zimpy";
banner="http://www.shareasale.com/image/468x60_green.gif";
alt="Visit SpreadShirt.com!";
}
if (ad==3) {
url="http://www.shareasale.com/r.cfm?b=66023&u=94808&m=7127&urllink=&afftrack=";
banner="http://www.shareasale.com/image/468x60_415.gif";
alt="Visit SpreadShirt.com!";
}

document.write('<a href=\"' + url + '\" target=\"_blank\">');
document.write('<img src=\"' + banner + '\" alt=\"' + alt + '\" width=468 height=60 border=0></A>');