I recently came across the following question posted by Paul Buchheit (the founder of Gmail):

Assume that I'm going to get rid of $20,000 and my only concern is the "common good". Which of these is the best use of the money: give it to the Gates foundation, buy a hybrid car, invest it in a promising startup, invest it in the S&P500, give it to the US government, give it to a school, other?

Many of our users donate money as way to do good with their careers, and I liked this way of posing the question - it's both broad and concrete. So I spent an hour writing out a rough answer.

I’ll take each option in turn and eliminate the worst ones, then compare a shortlist at the end.