I use an electric razor, but I don't shave it completely bald, just down to like an 1/16-1/8 of an inch, that way there's no razor burn. I'd say I do it about every two months or so, I let my hair grow out again till it's about an inch long and then off it goes again. The only tricky parts are (1) the back of my head/neck, 'cuz I can't see those areas well, even with a mirror, so I check those spots by feeling with my hand to make sure I didn't miss any spots, and (2) the annoying little hairs between your head and where your ears begin--it always takes me multiple passes to get those little bastards.
@WoodyXP: Damn, that's some fast shaving, it usually takes me at least 5-10 minutes to shave my head/face completely.