Yes, just basically a link to another page. If something like this
<a href="TARGET URL GOES HERE"><img src="URL of image1" onmouseover="this.src='URL of image2'" onmouseout="this.src='URL of image1'" /></a>
is best, then two images of 135px wide by 20px high would be used. The other example I gave used no JS, just CSS and an li class.
Which route is better?