I don't know if you're familiar with the Music Genome Project. It's an algorythm which analyses songs and compares them. So it can find similar songs. Pandora is based on this project. All you need to do is register and type in the name of your favourite song or artist and you'll find loads of music you never heard of and listen to it straight away. I play it alot. Note that it's only available in the US for now but you can register like you are from USA and type in an US zip code and you're off.