I could have thought of this, hook up an MP3 player to your doorbell. The possibilities are limitless. Now you can have Crazy Frog playing when the UPS guy is at the door.
Holds 64mb of mp3's, only plays's 1 MP3 (1.mp3). That's an full hour of FUN! Make sure you don't leave your house for more than an hour, and you'll know someone came calling for you.
More info on www.utuneit.com