I don't write about (or take advantage of) deals like this very often anymore, but this one is easy enough to be worth a quick mention.
If you registered in time for the current American Express "Offer For You" at Marriott Hotels, you can get a $50 statement credit when you make a single purchase of $200 or more at Marriott Hotels (excluding all their other brands: "The Ritz-Carlton®, EDITION®, AC Hotels by Marriott®, Autograph Collection®, JW Marriott®, Renaissance Hotels®, MOXY(TM) Hotels, Courtyard®, SpringHill Suites by Marriott®, Fairfield Inn & Suites by Marriott®, Protea Hotels(TM), Residence Inn by Marriott®, TownePlace Suites by Marriott®, Marriott Executive Apartments®, Gaylord Hotels® and Marriott Vacation Club®").
If you have a local Marriott Hotel (or if you'll be traveling near one before December 31, 2014) you should be able to buy a $200 Marriott gift card at the reception desk. Then use TopCashBack to click through to Cardpool.com and earn an additional $8 per $200 card, on top of the $176 Cardpool will mail you as a check. Earn $34 profit per registered American Express card (I have 5).
Cautious as I am, I'll be buying one $200 gift card first to make sure the statement credit posts properly. If it doesn't, I do have an upcoming Marriott stay which I can pay for with the gift card, rather than the points I was planning to use. That's less than ideal, but since Marriott Rewards points are seldom worth even a cent each on award night redemptions, I don't consider it a great sacrifice given the potential upside of the experiment.
Naturally, I'll report back once my statement credit posts (or doesn't).