Inbuilt camera for photos of high scorers is a good idea - cheap and obvious once you use an LCD display.

MP3 player capability - iDock and other connectivity makes sense.

When the Stern Cosmic Princess marketing campaign in 1979 or 1980, there was a photo of the machine with a little box that was rumored to take photos of players that attained high scores. It never took off - I never saw the camera box, or knew if it existed. Cool idea.

Sometimes, and innovation can be part of the ruleset. One part of Blackwater100 I loved was the multiball as soon as a game started. Adrenaline STRAIGHT from the outset.