Via Jim Plush, "After trying a bunch of bloated ajax frameworks I decided to write one that is lightweight and just takes care of the bare essentials to get things rolling. It supports XML, JSON, and TEXT formats: http://litfuel.net/mybic.
I'm looking for some volunteers to try it out and voice their opinions. The basic concept is:
one xmlhttp class that takes care of sending and receiving data and a php script on the server that acts as a front controller that all ajax requests go through.