American Express: Free One Time $15 Statement Credit on $75 Purchase from Walmart Online (Twitter Account Required)

To get this deal:
1. Click here and sync your Amex card to your Twitter account.
2. From your Twitter account, tweet #AmexWalmart to add the offer to your synced Amex Card
Note: be sure that you receive an "@ reply" message from @AmexSync stating that this offer has been added to your synced Card.
3. Make a single purchase of $75 or more with your synced card at Walmart.com by August 29, 2013.
4. A statement credit should be issued within 8 weeks after your qualifying purchase