Código HTML:
<script language="JavaScript"> <!-- function mouseMove(e) { var x = (document.layers)? e.pageX : event.x+document.body.scrollLeft var y = (document.layers)? e.pageY : event.y+document.body.scrollTop document.getElementById('Layer1').style.left=''+x; document.getElementById('Layer1').style.top=''+y; document.getElementById('Layer1').style.display='block'; return true } function init(texto) { document.onmousemove = mouseMove; document.getElementById('Layer1').innerHTML=''+texto; if (document.layers) document.captureEvents(Event.MOUSEMOVE); } function quitar() { document.getElementById('Layer1').style.display='none'; } // --> </script> <style type="text/css"> <!-- #Layer1 { position:absolute; top:148px; width:300px; background-color:#333333; color:#FFFFFF; padding:5px; border:1px solid #CCCCCC; z-index:1; } --> </style> <a href="#" onMouseOver="init('prueba')" onMouseOut="quitar();">asdasdasdads</a> <div id="Layer1" style="display:none;"></div>