Songbird
It is sort of a browser mixed with a Itunes with all the interesting things firefox has to offer like extensions etc.
I am typing this to you now from with in songbird while listening to some music I searched for in the software which then pulls it off the net.
If your looking to have just a little fun while you work then have a look at the Mozilla Songbird program.
Songbird - Open Source Music Player
Quentin