[Link] Duolingo
Yesterday I heard about an interesting new project called Duolingo. For some background, see this TEDx Talk by one of the creators, Luis von Ahn. It is a crowdsourcing approach to language translation, where the users learn a foreign language while translating. I've signed up but I haven't received an...
The board game "Wits and Wagers" might qualify for what you are looking for. Game play is roughly as follows: A trivia question is asked and the answer is always a number (e.g., "How many cups of coffee does the average American drink each year?", "How wide, in feet, is an American football field?"). All the players write their estimate on a slip of paper and then then they are arranged in numerical order on the board. Everybody then places a bet on the estimate they like the best (it doesn't have to be your own). The estimates near the middle have a low payback (1:1, 2:1) and the estimates near the outside have a larger payback (4:1). If your estimate is closest to the actual number or if you bet on that one, will get a payback on your bet.