Ajax is all the rage these days. Check out Rico, another collection of ajax/javascript widgets. Some really great stuff to be found here. Check out the accordion demo, I could actually use that for a project I’m working on right now.
It’s funny. 5 years ago I was so disgusted with the state of javascript support in browsers that I started actively avoiding using it. Things have come around though. There are still issues but the tradeoff is how cool and useful the things you can do are, and the issues mainly have to do with IE and its crap standard compliance which should hopefully be fixed in IE 7.