Exclusive Content for Multiple Release Games. (X360, PS3, Wii)
Soul Calibur has done it. Give each version a different character that can only be accessed in that version of the game. I like to see this because I own every system and it's nice to be able to pick a game based on the content. When all other things are the same or about the same such as the graphics, it can be hard to decide which version to pick.