Last game of mafia I played, something preaty amazing happend. I was framer, and at night, us mafia were chatting away, not thinking much about a spy. Anyway, the next day, suddenly 1 of the townies claims spy and claims that he knows who the GF is, and sure enough he's right, and ends up lynching the GF.
I looked back in the log, and none of us mafia had been so newb that we had said someones name. Curious, I asked the spy how he knew he was mafia (pretending to be a newbish townie). How he'd found out was in a way I never would have expected. He said that he had discovered that the guy was GF because he was the only guy in the entire game which always put a period at the end of every sentence. He saw that the GF always put a period at the end of each sentence, then the next day lynched the guy who always put a period at the end of each sentence!
Anyway, the morale of the story is that, despite Spy's haveing no abilitys, they can end up discovering highly useful information just by seeing the punctuation and capitalization the mafia used. They can do amazing stuff if played right, even vs Pro Mafia!