Basically, we came up with a design for a clicking-game, where each click generated a score. A random score. Except that these random scores were posted on an ordered leaderboard. I think one of my buddies even went so far as to implement it, mostly as coding practice. Unsurprisingly, people were happy to click multiple times in pursuit of a number high enough to warrant a spot on the publicly displayed list.
From a highly intellectual discussion of Cow Clicker, a parody of the Facebook farm games which is so close as to be an example of them.
Link found at Marginal Revolution.