The Cherry ML-4100 keyboard (mechanical, short travel switches) has about 90% key pitch (desktop keyboard generally have 19mm from center to center of keys). It feels decent to type on too, and is available in both PS/2 and USB.
I've also seen a few rubber dome boards with compact keys, a *few* of which are half-decent..... The old IBM M4 (rubber dome) was supposedly alright, though I never tried one. There's always the uTron board from Japan ($$$).
I think all the compact key boards are flat unfortunately. I prefer fullsize keys with different row profiles.....