For awhile I was thinking Herman Cain would be a good fit, but the way he exited the campaign makes me think he isn't an option. I hope he doesn't pick Santorum, and I doubt Santorum would accept anyways. Gingrich is also probably not an option, although I personally wouldn't mind. Ron Paul is probably not an option either.
So that leaves someone less well known, I suppose. Pretty hard to predict, I just hope it isn't another Palin type character.