Anything KHIII related.
More options and places where you can do Rumble Racing. And if they somehow refined it a bit in the PS3 version, kudos to them.
More Break Time Commands for TVA.
For you to be able to unlock Re:Coded attacks in BbS, if you watch the movie first (like Chain Raid, or something).
Some sort of reward for if you have a KHII saved file already on your PS3 (I know that most PS2 games don't work on the PS3, but they do on mine, and I'd really appreciate something like this).
The ability to choose what outfits your characters are wearing (for example, if you're playing BbS, it'd be cool to be able to you choose whether or not they're in their armor or normal clothes).
The ability to willingly go into Anti-Form (as well as being able to use the Command Menu, whilst you're in it), by unlocking that option somehow.
I think that's everything