I went from a 37" chest to a 33.5" chest. My shoulders atrophied tremendously. My biceps shrank to female levels too. The only thing I wish WOULD atrophy is my triceps. They've shrank but they're still a bit big. Everybody says I'm too self conscious about it and they look fine, but they're a little big for my taste.
As far as my butt, I have some size 5 jeans that used to fit me perfectly about 6 months ago, now I can't even get into them. I tried to pull on a pair of pants that used to be loose on me, now I don't even need a belt when I wear them. My butt (especially the sides on the lower hip area) has gotten quite fat...