Gavin has been working on an AJAX project in his "spare time". The project melds both his interest in roller coasters and the desire to demonstrate what's possible when you harness various Web technologies in new and creative ways. The resulting invention (coast2coaster) is quite amazing. You should definitely pick a park and switch to the satellite view. Doing so will allow you to zoom in and, in many cases, actually see the roller coaster. That's way too cool for words.
He's got a more detail explanation of the project on his blog. Sighhhhh. I guess this means that I'm going to have to publish something cool too.