AMEX Offers can be registered on all primary and secondary cards:
-Save $10 Off $50 At NYC Restaurants through 09/30 (People have also reported getting credits at jewelry stores and other stores listed on the restaurant map).
Twitter offers ending soon that can still be tweeted (see instructions here):
-Tweet #AmexDiapers, get $10 back on $50+ on purchases from Quidsi Brand stores like Diapers.com through 09/30. Terms.
-Tweet #AmexTravel100, get $100 back on $600+ on hotels from AmexTravel.com through 09/30. Terms.
-Tweet #AmexReebok, get $25 back on $100+ on purchases from Reebok.com through 10/03. Terms.
Deals ending soon that are only open to those already registered:
-Save $15 off $15 on Amazon.com through 09/30. Buy a $15 gift card here for free!
-Save $15 off $30 on Amazon.com through 09/30. Buy a $30 gift card here for $15!
-$25 off $250 on purchases from BestBuy.com through 09/30. Terms.
-$5 off $25+ on gas purchased at Exxon or Mobile Stations through 09/30. Terms.
–$20 Off $20 At SamsClub.com With Your Previously Registered Amex Card Ends 09/30