Това в <head>
[js]<script language="JavaScript">
<!-- Activate cloaking device
var randnum = Math.random();
var inum = 4;
var rand1 = Math.round(randnum * (inum-1)) + 1;
images = new Array
images[1] = "img1.jpg"
images[2] = "img2.jpg"
images[3] = "img3.jpg"
images[4] = "img4.jpg"
var image = images[rand1]
</script>
[/js]
Това на мястото на <body>
[js]<script language="JavaScript">
document.write('<body background="' + image + '" text="white">')
</script>
[/js]