In my fic I started to doing the 'rated R for (list reasons why I picked this rating)' thing. I do warn for excessive violence and rape (and because I have a friend who's an emetophobe, I will warn for vomit, though it's not something I've ever written). I also have all pairings listed so that people can figure out on their own whether it's het or slash...or both. :D Haven't had any complaints so far.