There's no mistaking when someone is at our front door. Our 1900's era apartment still offers a mechanical metal-on-metal doorbell which still scares the wits out of us each time someone rings it...it's that loud. How I wish we had this sort of subtle device installed instead.

Petersen's device is a unique prototype, so if you're looking for retail alternatives, here are a few to consider:

• Swann MP3 DJ Doorbell Brings Music to Your Ears and Door
  
• Pocket Doorbell Makes Ringing Friends a One Button Process
  
• Spore Modern Doorbells
  
• Wireless Doorbell Roundup

Via notcot

(Images/Video: Bobby Petersen)