DD was biting a lot a few months ago...and it seems to have stopped. I'm not really sure what I did to stop it though. I noticed that she thought it was hilarious when I screamed out "ouch"...so I stopped doing that and just quietly said "no" and gently moved her away from me and did my best not to reinforce the behaviour. It took time but it passed.
I think they're too little to connect their behavior to timeouts or other consequences. When DS bites, he does it when he's frustrated and/or testing us to see what we'll do. I move him to a different place and firmly say "No biting, I don't like that." If he comes back and does it again, I'll either move him or give him something to eat, or a nap, or something, because he's usually tired or hungry.
I think he bites for different reasons. Sometimes when he's tired, hungry or frustrated. But then there are other times when we're playing and he's in a great mood and out of no where he'll bite me. It's so frustrating.
Re: DS won't stop biting!