During my pregnancy with my daughter, I discovered that one of my breasts had an inverted nipple. My lactation consultant advised I wear the Medella soft shell.
This is a round, plastic device worn on the breast. The outer shell is a harder plastic, while the back is a soft plastic, with a hole that the nipple fits through. There are smaller holes so the breast can breath, and a foam piece comes, to fit inbetween the front and back, to catch any milk that could leak out.
Usually you wear this for a few hours at a time so the nipple can be trained to come out and not invert in. I really only noticed wearing it when I would lean against something. Since it was Febuary, I wore layers, and it was not noticable at all.
Cleaning is easyk, you just snap it apart, take the foam out and clean with warm soapy water.
I highly recommend it if you know your nipples are inverted and you want to nurse.