[StupidScript]

Here's pure CSS:

<style type="text/css">
.menu1 { background-color:#dedeff }
#menu1 { position:absolute;clip:rect(0,80,20,0) }
#menu1:hover { clip:rect(0,190,72,0) }
.menu2 { background-color:#ffdede }
#menu2 { position:absolute;left:100px;clip:rect(0,80,20,0) }
#menu2:hover { clip:rect(0,190,72,0) }
</style>
<div id="menu1">Menu Item 1<br />
 <span class="menu1">SubItem 1.1 | SubItem 1.2</span></div>
<div id="menu2">Menu Item 2<br />
 <span class="menu2">SubItem 2.1 | SubItem 2.2</span></div>