Currently there are over 2 million songs available, from more than 180,000 artists. Around 20,000 major and independent labels have signed up with Amazon, with EMI Music and Universal Music Group being top of the list.

"This new digital music service has already been through an extensive private beta, and today we’re excited to offer it to our customers as a fully functional public beta. We look forward to receiving feedback from our customers and using their input to refine the service," said Bill Carr, Vice President for Digital Music.

The list already includes many highlights, such as Beastie Boys, Coldplay, Creedence Clearwater Revival, Ella Fitzgerald, Keith Urban, Lily Allen, Marvin Gaye, Miles Davis, Nirvana, Pink Floyd, Radiohead, Rod Stewart, The Chemical Brothers, and The Rolling Stones.

All the songs are available in MP3 format encoded at 256 kilobits per second and may be played on any device the buyer chooses ( PCs, Macs, iPods, Zunes, iPhones and so on), due to the lack of software restrictions.

The price for individual songs ranges from 89 cents to 99 cents (more than 1 million of the 2 million songs priced at 89 cents), while most albums retail from $5.99 to $9.99.