Amazon has a promotion going on right now where if you order an eBook from their list of qualified books they will give you a FREE $1 MP3 credit.
This eBook is free and qualifies for the Free MP3 credit.
Just purchase the FREE eBook and Amazon will send you a followup email with the $1 MP3 credit.
You will get an email like this:
Additional information on this offer can be found here.
As a purchaser of a qualifying Kindle music book, you have earned a $1 Amazon MP3 credit. Your $1 credit has already been applied to your account is valid towards Amazon MP3 albums or single songs at http://www.amazon.com/mp3. For redemption instructions and additional information, click here http://www.amazon.com/mp3redeem. Amazon MP3 music is available to customers located in and with billing addresses in the United States. Taxes apply in some states.
The promotional credit must be used by May 22, 2012.