At the running store here, they actually sell "nip aids" or something...basically sweat proof band-aids for your nips. My husband swears by body glide. He has a few shirts that he won't work for long runs because of nip irritation. I was amazed the first time I went to actually see a marathon, the number of men crossing the finish line with bloody shirt fronts from nipple irritation.

The first man, I was shocked. The second, I was curious. The third, I was thinking...why hasn't someone invented something for this?????