QUOTE
Just a heads up, received a letter from American Express stating that if I spend $40 or more two times at walmart stores or walmart.com between Dec 1 - Dec 30 I'll get $20 statement credit. Although the letter stated this is by invitation only, it recalled me of the same offer American Express has run last Christmas season, during which a lot of SDers (including me) got their $20 credits few days after their 2x $40 spendings even though they did not receive the letters. So this is YMMV but worth a try...
source:
slickdeals.net/forums/showpost.php?p=25664837&postcount=39