<style type="text/css">
<!--
div#linktipp {
position : absolute;
}
div#linktipp a {
display : block;
}
div#linktipp a:hover {
background : white;
}
div#linktipp a span {
display : none;
}
div#linktipp a:hover span {
display : block;
text-decoration : none;
border-style : solid;
border-width : 1px;
border-color : black;
color : black;
background : yellow;
}
-->
</style>

Aufruf über Link:
<div id="linktipp">
<a href="dateiname.html">Linktext<span>Linktipp-Text</span></a>
</div>