I've made 2 home brew multicades now. Just messing around really. I think my next step is to just make a single player, 4-way joystick, 3 button multi. Then, a trackball only (but maybe work in a hidden spinner somehow). I agree, too many games with too many controls kills the experience.
I'd bet one of Pez's iScored hanging on a wall would really bring life to an arcade situation!