You Shall Know Our Velocity by Dave Eggers, a weird travel novel about two directionless twentysomethings who circle the globe handing out money to strangers for capricious reasons.
One of the novel's themes is the motivation behind acts of charity, and Eggers' protagonist offers a nicely quotable rant on the subject:
For every good deed there is someone, who is not doing a good deed, who is, for instance, gardening, questioning exactly how you're doing that good deed. For every secretary giving her uneaten half-sandwich to a haggard, unwashed homeless vet, there is someone to claim that act is only, somehow, making things worse. The inactive must justify their sloth by picking nits with those making an attempt --