var imgArray = new Array();

imgArray[0] = "/images/spot_ads/domino.jpg";
imgArray[1] = "/images/spot_ads/bio-baggie.jpg";
imgArray[2] = "/images/spot_ads/ultimate-tool.jpg";

var rand = Math.floor(Math.random()*imgArray.length);

function displayAd() {
	document.write("<img src=\"" + imgArray[rand] + "\" width=\"297\" height=\"220\" />");
}