r/music, if I knew of very few artists and wanted to discover new music, what should I do?

I have a pretty pathetic list of mainstream artists on my playlist. I'd like to discover new music. Pandora doesn't really do that, because it plays music based on what you already like. What would be amazing is if I could listen to a bunch of new songs, rate those, and then get a list of recommended artists to download. Does anyone know of anything that can help?