Ringtones of all types have been available for yearsnow. Now that common annoyance of customized tunes is available throughout your entire home with the ReBell USB doorbell.
Simply plug the ReBell into your PC and select a customized 30 second tune to play upon the arrival of a guest. The ReBell then wires into your existing doorbell system, so unnecessary wire-running is not needed. You can't go wrong with dumping a classic, retro video game tune into the ReBell, but for maximum efficiency, I would recommend a song by Journey so your guests would really know what goes down in your pad (back off RIAA, I legally own everywhere Journey album).
The ReBell is available from ThinkGeek for $100 and may require a smidge of technical/wiring know-how to install in your current doorbell system. Click the link below to see a comical video of the ReBell in action.