Have you tried lying down to nurse so the teeth are at least positioned differently? (Warning - lying down to nurse you child can lead to unintended naps.)
Don't worry that "it'll never be as much fun" - once they learn to adjust, you won't feel the teeth at all. At least that was the case for my 2 kids, and from what I hear on the websites for kellymom and la leche league, that's pretty typical. The usual pattern is, you get nipped a couple of times, but if you stick with it, the baby adjusts and everything goes back to normal. Even if you did absolutely nothing to discourage biting at all, they can't nurse when they bite down - the baby has to push his/her tongue against the roof of the mouth.
I agree with Dannelle about the nipple shields - they usually cause more problems than they solve.
Those 2 websites I mentioned have just oodles and gobs of information on breastfeeding:
www.kellymom.com
www.llli.org (la leche league)