I discovered Grooveshark only last week and I’m loving the service. The interface is easy to use, full-screen, and very responsive. It’s easy to find music and their library is huge. The sound quality is also pretty good. Not as good as high bitrate MP3 but hey it’s good enough. These days I’m pretty lazy when it comes to manually building up my library. I can simply use their “Popular” playlists to find new songs I might like. They even have a “Radio” feature that tries to add songs you might like based on the current songs you have playing. I was even able to find some Korean songs, so their library seems pretty comprehensive.