Railfans are building life-size, full-scale railroad cabs that look and function like the real thing, then projecting scenery onto their wall. And for music, you can hack their USB controller to turn it into a music / video / VJ controller, using either the Windows SDK (for hard coding) or a Mac app called junXion (for simple MIDI, useful with Max/MSP/Jitter, audio and VJ apps etc.) Aside from the train controller interface, you could use their I/O box to build any controller you wanted. There are other I/O boxes that use USB, but theirs has an unusual number of ins and outs, saving you basic stamp programming. And it’s also comparatively cheap. They also make bunches of custom controllers, keyboards, everything… Link.
Build a Better Music Interface: Railfans (as in Trains)