I'm looking for a resource of free Ajax scripts.

At this time I'm specifically looking for Ajax form scripts, but a resource of general Ajax scripts will be handy for future reference.

With regards to the form... Right now I'm looking for the typical Ajax, Web 2.0 form script where the "tick" image appears next to the input field when the value is correct, and an animated gif (Like this one - http://www.jamieharrop.com/loading.gif ) appears once the submit button has been pressed.

Any suggestions for where I could get something like this would be great.