I came across this great article at Smashing Magazine with links to a bunch of javascript controls. There are many great implementations of MooTools and jQuery. You can see the article.
I’m really into all the Mac-like script effects people come up with. Here are some of my favorites:
Slider Gallery (looks like the top portion of apple.com that lets you scroll through product lines)
It’s amazing how script has transformed the web so much in the last few years. I’d hate to think where we would be without it.