Below is a list of random AJAX resources from around the web.
Yahoo! UI LibraryYahoo has released a set of DHTML / DOM / AJAX components for use in your websites. Licensed under the BSD
AJAX FreaksHere is a site that I ran across that is a typical developer style site dedicated to AJAX. They have articles, tutorials, and forums. Could grow to a large community.
AJAX MattersHere is a pretty extensive list of AJAX sites, frameworks, articles and just general links to AJAX programming information. If you just want to explore the world of AJAX this is a good place to start.
Here is a new site that is getting started. The author Hazem Torab is collecting AJAX resources and tutorials from around the web and adding them to the site. Could become a great AJAX resource even if he did jack my tutorial word for word.
AJAX PatternsHere is a site dedicated to AJAX programming in the form of a Wiki. Looks like it has the potential to become a very in-depth site.
43 Useful AJAX Applications
I don't fully agree that everything on this list is useful, but there are quite a few good examples of AJAX on this site that show how AJAX can improve usability rather than just being Buzz-Word compliant.