Topic: people search
Not sure even why I wrote it but it's a site where you can put in a screen name, full name, email address, etc and find out more info about someone from other sites they've been found on. It's small and not too xajax heavy (just a search box) but it was the first time I threw xajax on a site.
Edit: oops. I never included the link! http://search.thenaterix.com