There is a theory, called Six degrees of separation, that anyone on the planet can be connected to any other person on the planet through a chain of acquaintances that has no more than five intermediaries. Based on this theory, there is a party game, Six Degrees of Kevin Bacon, which requires a group of players to connect any film actor to Kevin Bacon in as few links as possible. I have noticed that a more general Six Degrees of ..., has recently become very popular at the Internet Movie Database. I once even participated in this game. Finally, check out the Oracle.