Back again with another mega-list, Max Kiesler has posted this resource, a listing of 50 different Ajax toolkits and frameworks.
The following is a compilation of all of the AJAX toolkits and frameworks that I have either reviewed or have first hand experience with and would recommend. It seem like a new AJAX toolkit or framework has come out every week or so since the term AJAX was coined a little over a year ago. As a designer and developer I find these tools invaluable in the process of rapid web development.
Of course, the list is by no means comprehensive, but it does include both the "big names" in the framework/toolkit field (Atlas, Symfony, Django, CPAINT, Dojo) but also several of the smaller, lighter libraries the web has to offer (CFAjax, MyBic, Catalyst, Cajax).