Here are four examples of AJAX programming developed by Daniel Lorch that were presented in our AJAX lecture.
I looked at many examples on the web and these do a really fine job of illustrating the core concepts without much peripheral complexity. These code snippets are local examples of Daniel's code placed here with his permission.
Realize that without the benefit of the lecture, where I walked through these examples, it would be wise to go back to Daniel's page and read his explanation.
There is a Zip File containing these examples.