Billede, lav opacity, link, mus over.

<style type="text/css">
        a:hover {
            opacity:0.4;
            filter:alpha(opacity=40); /* For IE8 and earlier */
        }        
</style>

<form name="form1" method="post" action="">
  <a href="http://olsensweb.dk">
  <img src="ronols.png">
  </a>
</form>