Mgh0 spotted an article over at the Post-Gazette about a game designed to help computers learn to identify images.
In the game, which graduate student Roy Liu has been programming since September, one player is given an image and a word that describes the image or one element of the image. The object of the game is for the first player, designated as Boom, to get the other player, designated as Peek, to correctly guess the word.

Peek initially sees only a blank screen, but as play proceeds Boom reveals the image, little by little, by moving his cursor over the image.
The new game is based upon images used and tags created from another game Roy Liu wrote. Using people's need to pass some time with games, he's helping computers learn to see.

If you fancy a play, check out the Peekaboom website.