I've had fun with the API. I used it to download a bunch of data that I then fed into a system to correlate various things and display information for different parts of the country at several levels.

One of these days, I'll need to start it up again, set up a robots.txt to make sure the Googlebot doesn't crawl it (it has a lot of content generated on demand, including vector maps from shapefile data), and post it here.