I remember the guy across the street from me in Florida had a Burmese Python and his roommate thought he was going to get friendly with it. That snake bit him on the shoulder and really did alot of damage to him. Skin tears, bruising, the whole deal. Of course this snake was going on 8' in length as well. Shortly after that the snake was destroyed because it had gotten too wild for the guy to keep.
I work in the E.R. and we've had people come in with snakebites before. A couple were pegged by Ball Pythons. Of those, a couple managed to get the bite site infected and ended up with i.v. anitbiotics for a couple of days. I guess it all depends on how well you clean the strike site afterwards and so forth as well.
Had a rattlesnake bite come in last year as well. It was a "dry bite" and the girl was lucky. She was in the yard with her dog and went to sit down in the grass. The dog was acting reluctant to come over and she leaned over, putting her hand out on the lawn and startled the rattler. The snake struck between the thumb and forefinger, but again, it was a dry bite. She was kept in the E.R. for several hours though to ensure no ill effects settled in from the bite.
As everyone has said, cat bites and scratches are simply the worst. We admit patients all the time because of infections that set in after a cat bite or scratch. Cats are nasty and dirty animals that harbor infection in the mouths and claws. I love cats, but man, when I see what they can do to their owners, even when they are just playing, I'll take my iguanas and bearded dragons anyday and hopefully a ball python in the near future as well.