Oh, you might also want to disqualify prophecies that where fullfilled by one person's actions, if that person had prior knowledge of the prophecy (Jesus, I'm lookin at you - riding into Jerusalem on that donkey...)
That's an excellent point. Also, "prophecies" like in Daniel, where the earlier versions of the text don't contain the very specific "prophecies" that the later copies do, copies that only exist post-prediction. That is a case of clear retro-fitting of text to match events and is this NOT a prophecy.