May 3rd 2007 2:42AM Tigraine is almost 100% right: there's no AJAX involved, at least not in the public part of the site. I should actually remove those files from the site's public template since they aren't used.
The site is dynamic, with server-side caching, which explains the "smoothness". Requests which have been made in the past are served much quicker than new requests. Since everybody's looking for the same things (almost), there are very few cache-misses.
Ideally, I would have written this to be an in-game addon, but it was actually part of a grander scheme to show something to a client. Anyways, glad to see that it's helpful!
70 Elemental Shaman on Gorefiend, Jewelcrafter