Usa java script:
<script>
var max = 10;
var nrImages = 4;
function makeImages() {
this[0] = "http://i34.photobucket.com/albums/d109/cenourinha/1b02790f.gif";
this[1] = "http://i34.photobucket.com/albums/d109/cenourinha/1b02790f.gif";
this[2] = "http://i34.photobucket.com/albums/d109/cenourinha/1b02790f.gif";
this[3] = "http://i34.photobucket.com/albums/d109/cenourinha/1b02790f.gif";
this[4] = "http://bogasnetworks.com.sapo.pt/gethost4you_big_banner.gif";
this.length = nrImages;
}
function makeLinks() {
this[0] = "http://www.webtuga.com/index.php";
this[1] = "http://www.webtuga.com/top/index.php";
this[2] = "http://www.webtuga.com/forum/viewtopic.php?t=7363";
this[3] = "http://www.mais-trafego.info";
this[4] = "http://www.gethost4you.com";
this.length = nrImages;
}
var vetImages = new makeImages();
var vetLinks = new makeLinks();
var x = Math.round(Math.random()*max);
var y = max / nrImages;
for(var cont = 1;cont*y<= max;cont++) {
if (x <= (cont*y)) {
document.write("<a href="+vetLinks[cont-1]+"><img src="+vetImages[cont-1]+" border=\\'0\\'></a>");
break;
}
}
</script>