From experience, rubbing alcohol and a box of Q-tips works comparatively well at cleaning keyboards. Apply it with one Q-tip, then let the alcohol soak for thirty seconds to a minute. Once that's done, if the Q-tip's not too nasty, use it or a clean one to wipe up the goo.

It takes up fingerprint oils, stuff like that, and you can get down in between the keys. Of course, the keyboard I used it on was thirteen years old.