Two awesome (yes, much more awesome than gmusicbrowser) players/managers are in development. Well, Guayadeque is pretty much developed and is extremely usable, but a bit ugly. The ubuntu repo version did not work for me, hence I picked it up from the site – http://nchc.dl.sourceforge.net/project/guayadeque/guayadeque/0.3.1/guayadeque_0.3.1-natty-2_amd64.deb
Minitunes, otoh, is extremely pretty, but under extensive development. Fingers crossed. It is available in ubuntu repos.
Both are extremely fast:
gmusicbrowser – 80mb
guayadeque – 55 mb
minitunes – 60 mb
The best one as of now is Guayadeque. Go for it.