This is what we did, hopefully others can chime in:
I'm an advocate of prevention as 99% of the cure. I would offer to nurse like he's a newborn again-- rub the nipple from his nose down to his chin. It encourages a wide open mouth and lets you see his tongue better. A tongue forward in the mouth and over the bottom teeth is a nursing mouth. A tongue farther back in the mouth with bottom teeth exposed is a biting mouth. And if you really watch him for a while, you'll start to recognize which is which. If he goes to bite you, you can either put him down and end the session or you can rub the nipple over his mouth again until the tongue comes forward and he goes in with a nursing mouth.
If he gets upset about being put down, then your reaction is no longer entertaining and the game won't be fun anymore. If he's fine being put down, I would just let him go about his business. He'll come back when he's thirsty or hungry.
If you do get bit again, I really think non-reaction is the way to go. Don't say 'ow' or 'no'. Don't flinch. Don't jump. Just end the session and put him down. The only time I would explain anything would be if he gets upset at being put down. Then I would get down and say "It hurts mommy when you bite, and I can't nurse you when my feelings are hurt." Then you can offer to nurse him again to calm him down and repeat as needed until he doesn't want to do it anymore and either plays or chooses to nurse.
In regards to nursing down for the nap, are you sure he's tired? If he has enough energy to play the biting game and stand in his crib, I would just let him go about his business until he was tired enough to nurse to sleep and not bite. Your lo might be ready to change his own nap routine around. ETA: I know all babies are different in regards to this, though, and some always have to be coerced to nap. Don't know if that's your lo's personality or not.
Biting is a really difficult stage to get through, but they do get past it. Some go through multiple biting stages, but once you figure out how to manage the first one, they get easier to work through.
