Amazon seems to be offering a USD 1 credit for song purchases to their Amazon Prime customers if they are willing to take a delayed delivery.
Amazon Prime subscribers are entitled to 2 day free shipping on all shopping from the Amazon store.
This new option would let them take a delayed delivery for a free song from the Amazon MP3 store.
This is pretty cool for times when you are ordering a product that you can wait a couple of days extra for.
Delayed delivery option would mean that the product would be delivered in 5-7 days instead of 2 days.