I just realized that the Social Gaming stage is a wonderful ground for Trading Card Games. Trading Card Games are turn-based by nature, and the social aspect of trading card games is built in. I believe that if a good trading card system was made for a social networking site like Facebook, I think it would definitely do well. I'll definitely have to think more on the specific system I want to implement. I believe it would be best to have a system that allowed for easy drop and pick up card games.
For a Social Game, I believe one of two systems should be used. First it could be a game that is easily interrupted and a turn can be filled with actions, allowing enough complexity to make singular turns without an actively playing opponent to still be engaging and fun. Or a Second concept would be that games are short enough to be played easily and simply together, with your friends or a matchmaking system, much more like an arcade game.