Geosettr.com is one of the coolest games I have seen yet. It was mentioned at the FETC conference. You pick 5 places on Google Street view for others to try to guess. A link is generated that allows you to send the game to anyone. After you guess, the game tells you how close you were to the actual location. Do you know the place in the photo below?
Geosettr.com: A Game You Can Make to “Guess the Place”