Well as I mentioned in my post, AJAX is a very small part of most JavaScript frameworks even though people continue to just call them AJAX Frameworks. Anyways, below is a list of the most popular ones I know of. Please let me know if there are any JavaScript frameworks that are worth mentioning here. Aside from using the APIs in these frameworks, I still think its necessary to really understand JavaScript. As I mention in my post I truly think you are not a web developer unless you really know JavaScript.

• jQuery
  • Frameworks/effects librairies based on this framework:
    • jQuery UI
• Dojo Toolkit
• prototype
  • Frameworks/effects librairies based on this framework:
    • script.aculo.us
    • Rico
• Google Web Toolkit
• MooTools
  • Moo.fx
• Microsoft ASP.NET AJAX
  • Frameworks/effects librairies based on this framework:
    • ASP.NET AJAX Control Toolkit
  • General Info:
    • ASP.NET Client-Side Reference
    • jQuery ? That's right, Microsoft new ASP.NET MVC is using jQuery for client-side interaction and will actually be shipping it with the next version of Visual Studio.
• Yahoo! User Interface Library (YUI)
• Ext JS
• MochiKit