Step 1: Sync your American Express card with Twitter as described in this post.
Step 2: Tweet #AmexAustin10
Step 3: Check for confirmation that you are registered by clicking on @connect. (This can take a minute or so)
Step 3: Make a $5 donation (which is the minimum donation amount) to Austin Children’s Shelter.
Step 4: Shortly thereafter you will get an email confirming your $10 statement credit which should post within a week.
You’ll make a $5 profit by making a $5 donation on 03/13 only.
You can link more cards by opening more Twitter accounts.