The United Kingdom has challenged the United States to a Geography showdown. You can participate here. Each household can only participate 3 times per day to count for their country's score, but you can practice as many times as you like.
For a short while last night, Gus and I both made it on to the U.S. Leaderboard, but before you are too impressed, I have to admit that it took us an embarassingly large number of games to get up there. :)