V.K.
My daughter has been doing the same thing for about 2 years now (she's 2 1/2) and I am there with you where I am at my wits end. I have tried everything that is listed below but the one thing that seemed to do it was being very stern, putting her in her room til she stopped crying and was ready to say she was sorry and then taking her juice away for the rest of the day (only milk or water). She hasn't bitten me since and is starting to listen when I threaten to take the juice away again. I would try something similar to that. Take something that they like to eat or drink but don't "need" and take that away.
Good Luck,