AJAX
Ajax basics, development and debugging tools, JavaScript tutorials, xhtml crash course, data handling with JSON and XML, JSON-RPC, AjaxTags, and more. There are also separate sections on jQuery, Prototype, Scriptaculous, Dojo, Ext-JS (coming), and Google Closure (coming).
Live courses from the author: See the upcoming Ajax training courses in San Francisco and Maryland, for information on a customized version onsite at your organization.