Oh the things you can do with a Raspberry Pi. Here's one more option: Turn the tiny, inexpensive computer into a game console that runs a homebrew cross-platform game engine.
As you can imagine, this isn't a trivial project you can complete without some technical know-how. Guillermo Amaral, the engineer behind the Marshmallow Entertainment System (MES), has, however, shared his hardware specifications and the source code for this project. Still in development (there's no case yet and external USB storage may be added), the final build will enable the MES to be controlled by one or two Wii Classic controllers. Amaral built his own Linux distro, which as you can see in the video above, boots pretty fast.
See the whole MES system progress for ideas and the code to get started with your own DIY game console and Raspberry Pi.