Glenn Reynolds, aka Instapundit, aka "The Blogfather," writes:

People's willingness to make donations, sometimes sizable, in support of things they can get for free is something that has surprised me about blogging, and suggests that the portrayal of human behavior I got in Econ 101 was incomplete.

Too bad Glenn didn't take economics from moi. I emphasize early in my intro course that economics is not just about money, it's about whatever people value. So charity is perfectly consistent with economists' "portrayal of human behavior."