…but such a clever idea.
Google has invented a game to get people to label images with useable metadata. (Worth mentioning: the reason why google image search isn’t as good as regular google is that regular google searches text content – and images, well, they don’t have any.)
The game is this: you and another player are given a set of images, and you guess tags that you think the other person might use. When you both use the same tag (e.g. it’s a picture of a tree, and you both say ‘tree’), you get a new image. The agreed tag is added to the google database. Neat, isn’t it?
Unfortunately (predictably) some players are using the game to see how many pictures they can get tagged with a racial epithet. Yes, that one. You have been warned.