SongBird, the Open Source Media Player.
Songbird is a Proof of Concept (POC) open source media player that was born from the Mozilla Project and uses (XUL) XML User Interface Language which is the same language used for Firefox's UI. What makes Songbird really standout are a few features which should be familiar to Firefox users. One of those is the ability for user created extensions. User created extensions is one of the many reasons Firefox is so popular and gives the user the ability to create there own experience in the application. Another interesting angle is how Songbird presents the purchasing of online music. Instead of constraining the user to one service Songbird works with any online music service like iTunes, Amazon, Connect, Audible, eMusic, etc. As far as formats are concerned Songbird supports a whole slew of lossy and lossless froamts including MP3, AAC, OGG, FLAC, WMA and more. While Songbird is currently a Proof of Concept it will be something to watch out for.
A Songbird roadmap has also been posted that details some of the new features to to be included.