If you liked Brainiac, you will like Maphead; just don't try and read them to close together because in many ways they are the same book, interesting history of nerdery, intermixed with some Ken Jennings personal tales. This isn't really a problem, since I love Ken Jennings and his style, just it turns into a really long book if you try to read one after the other. Plus, the narrative isn't quite as compelling as his "I won a bunch of money playing 30,000 games of Jeopardy!"

However, Chapter 11 on Google Earth and such matters is worth reading just on its own, it's that good. And the rest of the book has that Ken Jennings flavor that I love so much. Also, it made me want to learn the capitals of all the world's nations. So there's that.