For a limited time, when you spend $50 or more on select items sold by Amazon.com in Apparel, Electronics, Software, Video Games, and Computers, you will get $10 off when you pay with your Discover Card. Items that qualify for this promotion will display a message under the “Special Offers and Product Promotions” section. After you’ve added qualifying items that total $50 or more and update your payment form to your Discover Card, the discount should be reflected in your cart. For the full terms of the promo, see this link. For examples of items eligible for the discount, see this SD thread.