Audiogalaxy was my music service of choice after David and others at school got me hooked on it, not the least of which because they had cool mp3s for legal download by artists I'd never heard of on labels likewise (except Four Tet's Everything is Alright, which was in that Nike commercial, and Croc says is on a buy-worthy album).
Rather than any of the bland news stories about its demise at the hands of the RIAA, here's the Kuro5hin article written by someone who worked there.