codice:
<script src="http://www.altervista.it/public/hdd_online/graficas/rainbow.js">

/*
Rainbow Links Script- TAKANASHI Mizuki
For full source code, 100's more DHTML scripts, and TOS, 
Visit http://www.dynamicdrive.com
*/

</script>
e poi sul link

onmouseover=this.bgColor=colorover