OK, I am Dwell's gf, who trained the cat not to bite me. She does bite Dwell *very* hard (breaks skin and once even bit his fingernail so hard it was bruised and dented for a week), but it's always b/c he provokes her during playtime.
Cxim: the method you described is absolutely repulsive--like Dwell says, there have been a lot of studies showing that negative reinforcement that subjects the cat to pain often does not work--and even when it *does* work, it takes a lot longer to train a cat in that method, not to mention the cat will associate YOU with the pain, rather than their own bad behavior.
This is one reason the water gun method/spray bottle works well--you can train a cat w/o use of pain, and also keep from damaging your relationship with your kitty.
Many professional cat trainers use the "clicker" method, coupled with rewards (i.e. treats or praise/attention). I think this is a lot better than ramming your finger down your animal's throat--all that teaches him is that you're a sadistic bastard who didn't read up on feline care.
I used to let Fatso (our cat) bite me all the time when she was a kitten, but once she got older and her teeth sharper, I decided to train her to stop. She was already full grown at the time, probably 1.5 to 2 years old (it's easier to train them when they're still kittens). My method was based on the repetition of the word "No" in a calm but very firm voice every time she bit me--once in a while I would try the "wounded cat" routine Dwell described, but if you do it too often she gets used to it and doesn't care that you're meowing in pain anymore--so use this technique sparingly. When I said "No" and she stopped biting me, I would praise her, but not touch her yet. I find if you give your cat a few minutes to calm down and just leave them alone, they will come back as affectionate as ever.
Anyway, she learned after a few weeks, and now she is so well trained that even when Dwell has her all riled up and biting him and wrestling around, if I put my hand near her she will jerk her head back and even though you can see she REALLY wants to bite me, she will run away and remove herself from temptation.
Pets.com has a lot of good articles written by vets on the subject of feline care and behavior (just go to Pets.com home page, click on "Cats" and then use the drop-down menu on the right which says, "Cat Article Topics"

. Here is one that outlines what to do if kitty is being overly aggressive:
http://www.pets.com/cgi-bin/puppy/editorial/editorial.jsp?BV_UseBVCookie=YES&oid=98962&parOid=-13273
And just in case you still are tempted to use negative reinforcement (please please don't), here is a quote from and the link to one more relevant Pets.com article:
"Never use negative reinforcement, or punishment, to train your cat. More often than not, he will associate the punishment with you, rather than with what he has done, and will learn to distrust you. Use positive reinforcement for the best training results."
http://www.pets.com/cgi-bin/puppy/editorial/editorial.jsp?BV_UseBVCookie=YES&oid=16179&parOid=-13273