Scenery nerds and systems nerds: MIT's Model Railroad Club
en.wikipedia.org
en.wikipedia.org
They build and program many things by themselves. Recently, they completed a very impressive addition: an airport, complete with starting and landing airplanes, cars etc. I listened to an interview with one of the founders, Gerrit Braun, where he says that for the airport alone they wrote several hundred thousand lines of code.
The airport: http://www.youtube.com/watch?v=Qz4NcTnQedo
Camera mounted on train: http://www.youtube.com/watch?v=RBArNAyODLc
Now if only I'd made it before MIT destroyed building 20.
You can see the tetris in action