If you happen to be close and friendly with a college student, buy their textbooks with the Amazon credit (if they were going to buy from Amazon anyway) and then have them reimburse you with cash.
I usually buy something on Amazon I'd normally get at the store...shampoo, soap, whatever is a good price match for your grocery store & has free shipping.
Then I take the cash I didn't use for the groceries to buy the Disney (or whatever other store) gift card.