aTunes is an open source iTunes alternative.  aTunes recently upgraded its version to 1.7.0 which includes radio support.  aTunes is able to play mp3, OGG, WMA, WAV, mp4, and FLAC files.  You can also rip and burn audio CD's with this application. aTunes integrates with AudioScrobbler and Last.fm to add the songs played to your profile.  If you are looking for a music player similar to iTunes this is a good alternative.

aTunes is available in multiple languages.

Album cover view.

Main controls for the player.  You can customize this to display in various areas of the player.

Menu for changing the look and appearance of aTunes.

aTunes is created with Java6 and Swing.  Developers can hop on board this project here!