This demo simply grabs text from another PHP file. Nothing much to see here, just demonstrating the basic concept.
This demo will check to see if a given username is valid and if it's present or not in a database containing existing usernames. This uses my "comments" database, so try "Sithlet" or "Jonny" for existing names.
Enter the name to check for:
Finally, this is something I've not done before in AJAX, but it's still pretty easy. This is very much like the AJAX on Digg. Below is the vote count as of whenever this page was loaded. Click "awesome" or "not awesome" to cast your own vote. The votes will then be updated from the database, so if someone else voted while you were wasting time reading this text, their vote will appear too.