Here's a link to some of the most common things people ask to do in this forum. I don't recommend using all of them in tandem, though, because you'd be more than likely to give your users seizures. However, some of them are nifty and add a bit of JavaScripted interaction to a page.

CNET\'s JavaScript Cool Tools

Coo beans!

I am looking for some "cool" cgi or php tricks instead of javascript though, but thats cool.