Created in 2003 to prevent the music industry from losing money on illegal downloading, iTunes has since sold one billion songs on its online music store. It offers individual songs for 99 cents, and, curiously, after paying off its partners, like the music labels, Apple just about breaks even. (The real big bucks come through via sales of the Apple iPod, which accounted for half of Apple’s $5.75 billion in revenue in the most recent quarter.) So, if you’re shopping around for places to help get your music out there, you might want to consider looking into iTunes and related services.