Joseph "Rawr" Thai's Mario-themed doorbell makes a coin-chime every time its pressed, and increments an LCD counter showing how many coins have been racked up by visitors to the house. Every ten presses, the doorbell plays a 1UP sound, and after 100 presses, it plays a mushroom upgrade chime.
Rawr's got detailed plans for building your own Mario doorbell.
Who wants a boring old doorbell that simply goes "ding dong" when pressed? I sure didn't! That's why I decided to design my own doorbell that provides ample entertainment for the guest at the door. Now, introducing the new Mario Doorbell; it's flashy, it's got coins, and it's guaranteed to increase the frequency of ding-dong ditchers or your money back! In fact, your guests won't even be at your door to visit you, they'll be too busy racking up coins to even notice you.