Amazon.com is offering a $2.00 MP3 credit when you use the promo code: CLOUDMP3! Go get the credit go here Amazon.com Cloud $2.00 MP3 Credit Offer. (thanks to sweetiesfreebies)
I used mine to download a free copy of Boyonce's "Single Ladies (Put A Ring On It).
You have the option of storing your music downloads on the Amazon.com Cloud and play it using the Cloud Player and/or you can download the music to your computer. You get 5 Gigs of free storage space on the Amazon.com Cloud.