A picture right as it senses deceleration would be cool, at the apex of the fall, just to see what the phone could see at that time. Video might be fun also, though I don't know if watching blurry spins would be all that enjoyable in actuality. The 3G is the only one that doesn't have real video capabilities, though that's nearly deprecated anyways. Last I heard, Apple isn't going to update it with the next major update. Whether that update is 4.3 or 5, I'm not sure.

To the OP, maybe you could use what you learned about using the accelerometer framework to make an app that background updates the movement of the user, and tracks approximate G-forces of elevators and driving, for example?