I’m currently using Songbird as my music player at work. It looks pretty cool — mainly I’m using it for the music library feature. It’s basically iTunes but open source.
A happy coincidence/side-effect to using this is that installation effectively solved the sound problems I had with sites such as YouTube. No sound from flash stuff.
If you’re having issues under Linux with flash sound, this link may help you out. It basically boiled down to installing some extra gstreamer plugins and whatnot.