/*Here's how it's done. 

In every case, the "caption" text is a span element inside the actual hyperlinks. Here's one example from the source of this document: 

<a href="http://www.meyerweb.com/eric/css/">Links<span>A collection of things which interest me, and might interest you</span></a>

div#links a span {display: none;}

div#links a:hover span {display: block;
   position: absolute; top: 200px; left: 0; width: 125px;
   padding: 5px; margin: 10px; z-index: 100;
   color: #AAA; background: black;
   font: 10px Verdana, sans-serif; text-align: center;}

div#links a:hover {color: #411; background: #AAA;
   border-right: 5px double white;}
*/
div#links span span {display: none;}

div#links span:hover span {display: block;
   position: absolute; top: 185px; right: 120px; width: 290px;
   padding: 5px; margin: 10px; z-index: 100;
   color: #000; background: yellow; text-decoration: none;
   font: 11px Verdana ; text-align: center;}

/*div#links a:hover {color: #411; background: #AAA;
   }
   */