I use a Scala Rider bike to bike intercom with my wife, so that we can talk as we ride along, and also so that when we are riding alone we can listen to the radio/music via phone, or even receive phone calls on the go.
Most the time i don't bother with the radio/music, unless i'm on a long ride, otherwise if i'm on the ride with my wife we tend to inform each other of directions, and overtakes and any hazards we've come across, as the headsets have a range of about 2Km's