Pandora

Pandora on Facebook will let you enjoy music you already know and help you discover music you'll love. Find your favorite songs or artists and create personalized stations that play full songs, keep tabs on your friend's musical interests, and fill out your profile with music samples and favorite artists.

Pandora is powered by the most comprehensive analysis of music ever undertaken, the Music Genome Project: a crazy project started back in early 2000 to capture the complex musical DNA of songs using a large team of highly-trained musicians.