Engadget just introduced us to DoorLinX, the world's first mp3-playing doorbell system from NetStreams. It has an integrated microphone, a speaker and, of course, the outdoor trigger button. The unit is operated with the help of a Streaming Music Manager, which locates and streams music for the operation of the doorbell. The release date is "soon" so we don't have a price yet, but being able to customize your doorbell in the same way you can customize your mobile ring tone seems like a great way to add some more individuality to your home.