You could argue the same about Youtube, in some sense.

They do pay royalties to some artists, and at least for a while a lot of upcoming artists were advertising their new albums there. I discovered a bunch of great groups through that.

Unrelated with revenue, but I liked how some artists (Avicii comes to mind) ask you what do you think about X song when you play it in Grooveshark, that's some valuable direct feedback. The radios are awesome too.

Can't hide the fact I've been using it for years, but I truly think Grooveshark is the best music streaming service by far. Spotify's catalog is nowhere as large, Pandora misses on so many features, Last.fm recommendations are good but what else do they do...