I am lately interested in the Raspberry Pi as a gaming platform. And say what? There are a couple of interesting projects doing exactly this. There is for example Cave Story available for the Raspberry! Between other goodies, browse for example the game-tag at the Raspberry-site.
Another cool project seems to be the “RetroPie-Project“. This is a dedicated Raspberry-distribution, that aims at turning the Pi instantly into a retro-gaming console.
Got more interesting project? Feel free to leave a comment!