Don' wean! It is a phase. Here are tips that worked for us
Be careful not to reinforce the behaviour. Some moms have yelled and their baby has gone into a nursing strike. Or the baby thought it funny and wanted to continue getting a response.
A few suggestions in the Breastfeeding Answer Book
pull the baby in close so they will release the nipple
giving him a frozen washcloth or other acceptable teething object quickly put the baby on the floor when they bite, after a few seconds of distress after being put down, the baby can then be comforted and should get the message that biting brings negative consequences
The baby associates feelings of comfort and security as well as satisfaction of hunger with his mother. He does not understand that putting his teeth on her nipple causes her pain. Babies do not bite out of meanness. A bab has to learn what to do with new teeth while nursing, and this sometimes learned by trial and error.
Whenever he bites, immediately end the nursing. Take him off, say "ow" (but without too much of a guilt trip), stand up, and move on to the next thing. Don't start nursing again for a few minutes, even if you had just begun. Just nicely do something completely different with him for at least 5 minutes.
Second, if it's getting near the end of a nursing, watch him like a hawk. You'll probably see some signs that he might be getting ready to nip. He might lose interest or his tongue might slip back in his mouth instead of being out at the edge of his lower lip. (He can't really bite if his tongue is where it should be.) If you think he's slowing down, take him off and end the nursing.
I feel for you, those litle first teeth are pretty sharp. Hang in there. It gets better, I promise! Now mine has 16 teeth and hasn't bit me in a year.
And I dont agree with the posts that the baby has gotten all the benefits of breastmilk now. That is not true! There are so many benefits of breastfeeding a toddler
http://www.kellymom.com/bf/bfextended/ebf-benefits.html