What do you do when you have a scriptable Super Nintendo emulator ? You create a program which teaches itself to play Super Maria. *duh*
You may know SethBling from his Minecraft creations, or as a Super Mario speed runner, but my favourite thing so far has to be MarI/O. It's a neural network implemented in Lua running inside the SNES emulator. Given enough generations, and the right scoring function, it figures out how to beat Mario levels:
And he shared the source code, though sadly without a clear license.