Everybody is talking about AJAX (more explanation here) these days. It’s a combination of JavaScripting, css and XML and/or any text data. To find the most obvious demonstration of the technology, look no further than Google Maps. The advantage of implementing AJAX is that the user doesn’t have to refresh the web page to see the information he requested being fetched. Good stuff.
I found a site with some interesting sample codes for all you AJAX-programmer-wannabes.