youtube has everything and its free but i do use Pandora on my phone and have tried grooveshark
for me it has to be gaana.com(still in alpha). Unlimited free streaming of music..
amazon for singles
I still buy the cd's from my fave bands
I am a subscriber to Spotifys "Unlimited" service in the UK, for £5 a month, unlimited add free music is a bonus, I don't have expensive speakers so am fine with the 128 bit rate cap, (For £10 a month its 320) I have been a spotify user since the Beta, was on the free service untill they capped it.
http://www.iomoio.com/ 16 cents a song fixed rate and perfectly legal. Made in Russia
Edit: Actually, the more you deposit at a time, the more of a bonus you get. So by transferring $96, you actually get each song for 8 cents a piece.
Spotify i have the premium service for 10 bucks a month and its epic
amazing..that "NO ONE" mentioned the use of blogs to discover new music....thats a service