OK, I kept this one to me for over a year now, but as I have just been reminded that this is the only free music site that pays for its content in license fee and is legal I thought I will share it with all.

Update: Use BetterGrooveshark userscript with greasemonkey to have lyrics instead of adverts.

Visit: Grooveshark – Listen to Free Music Online – Internet Radio – Free MP3 Streaming.
Sadly the Android app was pulled recently from market but grooveshark are fighting back.