aTunes: Cross platform, open source media player
The program has all the features you'd expect from a modern media player, including the ability to play MP3, ogg, WMA, WAV, FLAC, MP4, RA, and RM files. You can also listen to internet radio streams. There's no support for DRM though, so if you've got restricted music files on your desktop, this might not be the player for you.
One of the niftiest features in aTunes is Last.fm integration. While you can't use the software to play music from Last.fm, you can sign into your account and submit your played song list to Last.fm. aTunes also takes advantage of Last.fm's audioscrobbling service, which means you can see a list of artists that are similar to the one you're listening to in real-time. When available, aTunes will also automatically display album art and song lyrics.
Update: It appears the web site is down, but you can still download aTunes from SourceForge.
There are far too many features to list them all, but here are a few of the cooler ones:
- Karaoke function (which cuts the frequencies typically used by the human voice and lets you sing along at the top of your lungs)
- Tag editor window
- Drag and drop support (drag files from your file system into the player)
- Support for portable devices that can be mounted as a file system
- Search for artists on YouTube, Google Video, Wikipedia
- Subscribe to podcasts
- Built-in CD ripper
- Tracks statistics such as songs played, not played, songs, artists, and albums most played, and last date