stienman writes: "Everyone in the US knows that if you dig straight down, you'll end up in China. Except you won't — instead you'll end up swimming. Spurred by this question I used Google Maps to show where you will end up if you dig straight through the center of the earth. This antipodal geography tool is easy to make and fun to use. What other fun and informative web-based geography tools have you played with? What age-old questions could be answered in an hour of simple programming with free mapping tools?"