The Sixty One is an awesome little internet radio station that plays mostly underground stuff.
Mumford and Sons
Florence and the Machine
And a bunch of other stuff (I just found out about it so I'm not totally sure exactly what they play)
What's cool is a lot of the songs are free to download and you can select different moods or just play the top stuff. You can also comment, love, and create playlists.
Sorry, this station/website isn't gangster friendly, so you won't find your Wu-tang and Biggie on there.
I searched and didn't find anything so sorry if this is a repost. If so, just let it fall to the bottom.