Google (book) maps

Speaking of representations of the planet, this clever fellow at the Google booksearch blog decided to compile the geographical settings of books for the past 200 years (or at least the place names mentioned in them). Decade-by-decade maps also show the western migration in the early 19th century.

Mostly these points trace where people live, but there are so many cool things you could do with this data. I would like to see the difference between novel settings and actual population density. Britain especially, seems pretty over-represented. Different maps for different genres would be fairly interesting as well. Get on it google!