I totally agree 200% with Lansinoh ... It's pure, 100% natural and safe for babies when you nurse (no need to clean it off). It's lanolin, which is a waxy "substance" given off from sheep. It's very thick, though, so if your nipples are really sore/cracked, I recommend you put a small amount between your thumb and another finger to warm/soften it before applying. It's kind of expensive, but worth it and it goes a Looooong ways.
As an added note, it's great for cracked heels, elbows and other such problem areas. You can get it pretty much anywhere - Walgreens, CVS, WalMart, etc... It comes in a purple container.
It was a life saver for me. I would apply it after each feeding, and about 15 mins. before each feeding and definitely between feedings. (so, yeah.. pretty much 24/7) hahaha
Also, try not wearing a bra if possible for a few hours a day so the bra doesn't chafe and gives your nipples time to "breathe".
Best of luck... let us know if you try it and if it works for you.
Congrats on the baby, mama!