American Express is offering double points when making Amazon.com purchases through May 16, 2016. UPDATE: It looks like this might be a targeted offer.
This is an Amex Offer, so you’ll need to sign into your AmericanExpress.com account, go to the “Amex Offers & Benefits” section, and click the “Add to Card” for the specific Amazon offer. This offer will only be available on credit cards that earn Membership Reward points, i.e., American Express EveryDay, American Express Platinum, American Express Premier Gold Rewards, etc.
For those that make purchases at Amazon.com, this is a great way to increase the number of points you earn. Of course, your best bet to really maximize the points earned is to buy Amazon gift cards in advance from an office supply store (i.e., Staples) with a credit card that earns 5x points (i.e., Chase Ink, American Express SimplyCash)