Wasn't it proven that the human body can't be supported by nails in the hand, and that it would more likely have been done to the wrists?
I've read the same, though I cannot remember where.
National Geographic did a TV series called Taboo. where they profiled some activity that seems strange ("taboo") to most Westerners, but are perfectly normal in other cultures. One of the episodes was about people having themselves crucified in the Philippines. They focused one man who promised that if his wife and daughter survived the daughter's birth (it was a rough one), he would have himself crucified for 10(?) years. Wife and daughter lived, and he was on crucifixion #10.
I managed to watch the episode, but it was rather creepy. (Not too graphic, though. No shots of him actually getting the nails driven in.) From the look on the participant's faces, though, it's clear they weren't having much fun.