It's something that I only would use once or twice a year, but it's still a nice feature. It cost Amazon little since it's simple linking your account to music they have already setup to stream.
Amazon "Cloud" Player
So I just bought a CD from Amazon for like $4.99 and it says you get a free download of your CD on the Amazon Cloud Player. So I download the player and go to listen to a preview on the Cloud player and when I open it up - there's a sh!tload of music in there. But familiar music. Hmmmm. Then I realize, Amazon loaded every CD I bought from them into the Cloud player. Years of cd's are automatically and instantly loaded in there. Really incredible. Unfortunately, it sounds like sh!t. Worse than MP3 quality I think. At least that was my initial impression. Still, it's a very nice gesture on Amazon's part. The average person wouldn't know the difference anyway. I'm definitely impressed with their effort.