If you're looking for a library of AJAX controls, you should check out
jsObjects. These are all controls I wrote that are simple to add to
your code, and take only a few lines to put in place. They'd make a
nice compliment to this Yahoo toolkit, and they're free. I've got a few
users around the world, and I'd love to see more people putting them to
work and providing feedback.
AJAX rocks and it's great to see a big company like Yahoo contributing.
Check out jsObjects at http://software.jonandnic.com/jsobjects