I'm a big fan of the free internet radio platform Pandora. You plug in a song and artist and through the magic of musical genomes it finds other songs that you'll like. You then rate the songs with thumbs up or down to tell Pandora more about your tastes. I've found out about a lot of artists that I never would've discovered otherwise. I find that it is pretty effective if I spend some time with it. I wish the whole world worked that way. Like when furnishing my new apartment I could just pick one item I like and then be shown lots of wholesale housewares that I'd also approve of.
My favorite Pandora stations are:
Frank Sinatra. Even though I'm 26 I listen to this station a lot when I'm working or need to be mellow.
Cloud Cult. This band has put out more albums than I initially realized. I like to see how their sound has evolved over time.
Eve 6. I only let alternative 90's bands on this station. It's great for nostalgic purposes.