Amazon has lots of items that claim bonus dollars for Cloud purchases. Take for instance Fabled City by the The Nightwatchman.
Special Offers and Product Promotions Buy a CD, get $1 in Amazon MP3 Credit. Limit one promotional credit per customer. Here's how (restrictions apply)
How do I find out how many of those $1 credits I've accumulated? I know I must have a bunch. It says Limit one promotional credit per customer. Does that mean one promotional offer per sale of item that has promotion? Or does it mean one promotional offer for all items that have had this promotion? I've been buying items marked with this text for a year—is it all part of one giant promotion?