There actually seem to be a number of decent Ajax packages
out there right now. I've started working with SPRY, which is
Adobe's ajax package (currently in pre-release). It has some pretty
neat features and effects, though being a pre-release product it is
still working out its kinks. Still, the forum is very helpful and
you can usually get a response from an actual Adobe team member
quickly.
http://labs.adobe.com/technologies/spry/
The main feature of the framework is the ability to treat XML
documents as datasets (think CF queries) and create page regions
that dynamically update when the data in the dataset is selected,
changed, filtered or sorted. The examples can give you a better
idea of what I'm talking about. Basically, the only big drawback
right now is 1) Currently no support for multiple levels of nested
XML elements (though they are working on it) and 2) No back button
browser support.
Anyway, worth checking out if you are looking into Ajax
packages.