A bold barbarian walks onto town past a punished naked slave girl on a rack, while at far right, the oldest whore in the village looks on. Image source: photomanip of an image from Skyrim with an image from Second Life, created by me.
After introducing you to naked slave girl invaders in Dragon Age and Oblivion, I've found the mother lode: Lovers Lab, a message board site dedicated to adult mods of various games, with sections devoted to Skyrim, Fallout 3/New Vegas and Oblivion, and boards for other games and sections for popular adult mods as well.
You can find out where to find the latest mods (for non-gamers, "modifications of game features, such as avatars," discuss issues in game modding and socialize with others who enjoy adapting games to their own purposes. I had no idea things had gone so far so fast in games outside Second Life, but I shoulda knowed, I guess. Check it out!