Maybe Guayadeque and/or Quod Libet? (I use both, neither are really pretty, though, but handle large libraries easily). Occasionally I use audacious, too, not sure why it doesn't get a lot of love, it's simple, light, and recently has gotten better. http://guayadeque.org/ http://code.google.com/p/quodlibet/
Unter Linux habe ich mal lange Guayadeque verwendet. Ich hatte so einen alten P3-Laptop, den ich als MusicPlayer wiederbelebt hatte. Lief erstaunlich flott auf der alten Kiste und hat genügend Features dabei.
Mittlerweile ists meistens Audacious, weil ich dazu tendiere, ganze Alben zu hören, deshalb reicht das.
I've tried a lot of music players, but I always come back to Rhythmbox become it's just so rock-solid. I never have any issues with it.
However, the latest challenger is Guayadeque, which I really like so far.