According to an article by USA Today.com, the Amazon MP3 store has become the second largest digital music service in the United States. Amazon’s much anticipated digital music service was launched in 2007 and began selling its entire catalog in the unprotected MP3 format. Initially, the store had a catalog of 2 million songs but this has now increased to over 4.5 million - this is quite staggering since the service has only been in operation for approximately 6 months.

The reason for their speedy success can be attributed to excellent marketing through the use of consumer-friendly MP3 downloads and aggressive pricing that even forced Apple's iTunes Store to lower its price of DRM-free songs.

For more information, read the full review of the Amazon MP3 Store.