Amarok (formerly known as amaroK) is an audio player for Linux and other varieties of Unix. It makes use of core components from the KDE desktop environment. It is released under the GPL and is bundled with many distributions that use KDE as the primary desktop environment.
I use iTunes on OS X but I can also listen to music with Amarok when I'm on Linux.
Amarok is the world's best music player and organiser. It will obliterate the evil iSpoons in one fell swoop.
The new Amarok SVN is out.