Right now through 5/24 you can get a FREE $2 Amazon MP3 Credit! In order to receive it, you'll need to share your favorite song on Facebook to add the $2 credit to your account. Your credit must be redeemed by 11:59 p.m. PST on 5/24. Limit one promotional credit per customer.
With Amazon MP3 you can buy a single MP3 starting at $0.99 or use this credit to get a discount on a complete album.