Here’s one for the Java crowd, which seems to be increasingly adding support (via libraries and frameworks) for Ajax in java-based web apps.
Paul Brownse of java.net has an extensive tutorial on ajaxifying your struts app:
AJAX is the latest revolution in web development circles, allowing rich dynamic interfaces deployed within a normal web browser. Struts has been one of the de facto standards for Java-Web development for a number of years, with a large number of applications already deployed. This article will show you how to combine the richness of an AJAX user interface with your existing Struts applications.
Here’s a flamewar starter poll: Which web programming platform / language has the best support for Ajax?