ClrMamePro is a must have for any MAME or MESS user. The GUI is a little confusing, in my opinion, but easyEmu has created a very nice tutorial to help out new users. One of the nicest features is the ability to create fix dats. These can be used to compare have/missing roms from your set with those of a friend's set.
I've make it with wineskin winery for my personal use and i made it public for all who want to sort romset without bootcamp or other kind of software to run win on mac.