I use mine as a media player (raspbmc) whilst polling some temperature sensors in the background to monitor my turtle pond and output to cosm twitter and an xk3y remote.
Ive also ran the chip8 emu using the xk3y remote as input and screen that was fun for a short while, Its also fun just making them talk .
But using a Pi as a 3ds unbricker has to be the most awesome use of a Pi I have seen in awhile
http://gbatemp.net/threads/nintendo-3ds-unbricking-is-possible.361240/ since it makes the Pi a useful tool rather than a novelty toy.