Никаких скриптов:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=windows-1251" />
<style type="text/css">
.myDiv {
background: #777;
border: 1px silid #CCC;
border-radius: 20px;
color: #DDD;
font-size: 18pt;
font-weight: bold;
height: 70px;
left: 50%;
margin-left: -150px;
padding-top: 30px;
position: fixed;
text-align: center;
top: 100px;
transition: top 0.5s;
-moz-transition: top 0.5s;
-o-transition: top 0.5s;
-webkit-transition: top 0.5s;
width: 300px;
}
.myDiv:hover {
cursor: pointer;
top: 20px;
}
</style>
</head>
<body>
<div class="myDiv">Наведи на меня!</div>
</body>
</html>