I remember back in college there was a program for the Mac that was floating around called Talking Moose. If you left your computer idle for a while he'd pop up and say something random. It was pretty silly and would drive people insane after a bit. I know of someone who used to use it to help keep them awake during allnighters. Mostly though, Talking Moose was one of the most useless programs out there, but it was funny to play with now and then. Alas, I thought the moose long gone.
Then, this afternoon I suddenly decided to type 'Talking Moose' into google (after reading about Jarod over on Perversion Tracker. Not only did I discover that the Talking Moose still exists, but there is a version of OS X. My laptop will never be the same.