Songbird

Songbird is open source and supports user contributed, cross-platform extensions. With a sleek, yet simple interface, Songbird really shines with its integration of add-ons. With the ability to link to sites like Last.fm, Songkick Concert Guide, and the 7Digitial Music Store, now when you listen to a song, you can let your friends know what you're listening to, search for upcoming concerts and song lyrics by the artist, or buy more tunes from your favorites, all in one place.