A friend of mine and I gave a presentation on AJAX about one and a half weeks ago, so here is the material in case anyone might find it useful. The part that should be most useful would be the presentation samples which contains a working web application that runs out of the box in an Apache Tomcat installation. So, if you want to get a start on AJAX, give this a look because the code should be more than clean enough for the newbies out there.

Download the presentation samples.
Download the PowerPoint presentation.