function banner() {
};

banner = new banner();
number = 0;

// bannerArray
banner[number++] = "<a href='http://www.cetacanyon.org' target='_blank'><img src='http://www.welcomepardner.com/uploads/images/ceta_canyon.jpg' border='0'></a>"
banner[number++] = "<img src='http://www.welcomepardner.com/uploads/images/acn_draft2.jpg' border='0'>"
//banner[number++] = "<a href='http://www.url4.com' target='_blank'><img src='http://www.cgiscript.net/images/banner-4.gif' border='0'></a>"
//banner[number++] = "<a href='http://www.url5.com' target='_blank'><img src='http://www.cgiscript.net/images/banner-5.gif' border='0'></a>"
// keep adding items here...

increment = Math.floor(Math.random() * number);

document.write(banner[increment]);