AJAX is a now a well established technology. It has been around for a long time but only recently (2005) was the term ‘AJAX’ coined to mean Asynchronous JavaScript And XML and unify the previously disjointed technologies it represents. Essentially it is an amalgamation of technologies to provide good user interface tools for Web browser applications.

Now of course there are a myriad of these toolkits, most born soon after the publishing to the AJAX article in 2005, and most not really suitable IMHO for real application. But they are all useful to look at. For me the most interesting ones are the following:

• Behaviour: A clean approach to AJAX
• Prototype: Perhaps the best AJAX base available
• Mochikit: Very useful, clean AJAX framework to start off with
• Script.aculo.us: Toolkit full of widgets for general interface construction
• Dojo: A toolkit focussed on object manipulation and widgets
• Spry: A semi-commercial AJAX library in keeping with all things Adobe (BSD licence)
• Kabuki Ajax Toolkit (AjaxTK): The best semi-commercial AJAX library available from Zimbra

There is pretty good AJAX web site here if you need a place for starting to look for AJAX resources.