The Listener Network is an exceptionally useful and well-designed initiative, unveiled by Rhapsody (formerly Nampster), that is designed to make it easier than ever for users to find new songs, artists and albums based on the music that they already enjoy.
The service makes use of a number of different kinds of data to help you find new music, one of the most fundamental being the Music Match feature. Music Match is capable of looking at all the music you add to your library and compare your listening history with that of other users. This means that you can effectively see to what degree your musical tastes overlap with another users, making it easier than ever for you to decide if you want to follow a particular user or not.
What's great about the Listener Network is the fact that it helps you assess your equation with other users, helping you discover familiar or new music, whatever your desire may be.