With iTunes 5, Apple introduced Party Shuffle, which randomly picked songs from a user's music library or specific playlists. It proved extremely popular with iTunes users. Embarrassed that Ace of Base's "The Sign" might make its way through your speakers at a party? Simply check a box to remove it from Shuffle consideration.
Three versions later, the feature was renamed "iTunes DJ," and allowed friends to request songs through their mobile devices. Apple killed off the DJ in the most recent version, iTunes 11.