The Guilt Pledge
Watkins and Brook have another great editorial out at Forbes. I really like this paragraph, but be sure to read the whole thing:
But your wealth was not an undeserved gift. Every dollar in your bank account came from some individual who voluntarily gave it to you--who gave it to you in exchange for a product he judged to be more valuable than his dollar. You have no moral obligation to "give back," because you didn't take anything in the first place.