I've used Son of Suckerfish for a drop down menu - see
http://www.htmldog.com/articles/suckerfish/ for the walkthrough and examples. It's mainly CSS with a little bit of javascript, but it degrades nicely for users without javascript. I don't have a live site to show you though as I'm still working on it (it's not a website so much as a web app).
Can't give you any idea on image rollovers... as I haven't really used them... but it really depends what effect you're trying to achieve? If they're links you could be able to do it easily enough with CSS alone shouldn't you?