rewboss - 9:49 am on Aug 9, 2002 (gmt 0)

A simple rollover script is all I regularly use, mainly because it makes using the site slightly slicker and a bit easier (especially when the buttons are small) and people have come to expect it. But even a rollover script can be replaced by transparent GIFs and a nifty CSS a:hover{background-color: ....}

Simple form pre-processing and validation is also useful. It can't actually replace a server-side script, but it's probably a nice user-friendly touch to catch certain errors before the form is submitted. This also reduces load on the server.

Basically, though, I think you should arrange to make sure your site is functional without JavaScript; so nothing critical to navigation should be JS.