If youve seen those coin drop arcade machines, you know how enticing they can be. They make you think "Just one more coin and Ill win..."
This is a coin drop machine: http://www.youtube.com/watch?v=tnG7fg_SPq8
I think this is a great idea for a DAC. The wallet would have a 3D simulation of a coin drop game, and users can drop their shares in and watch them bounce around. It would cost 1.1 shares for each play of the game - 0.1 for the transaction fee, and 1.0 for the coin dropped into the game. The dividends would be HUGE.
You could also drop BitAssets in such as BitUSD, BitGLD and BitDOGE. They would make the game more interesting and would have the same function as the gimmicky prizes you often see in the real coin games.
3 design issues:
Because user commands have to put into a block which is created every 10 seconds, the game wouldnt be real time. You could setup a scheme whereby the virtual coin pusher begins and ends in "phase" with the block times. This way you submit your command to drop BitUSD into the coin drop at 5/10 through the current block, and you see your coin drop at 5/10 through the next confirmed block. Because of the time delay, its possible that the game might not be as fun.
To validate the blockchain, potentially a lot of expensive physics calculations would have to be done, and they would have to be deterministic. A fixed point physics engine may help here.
What happens when 2 users throw in a coin and win at the same time? How are the winnings divided?