A smile. Note that there are a lot of things many people are willing to do for free but wouldn't do for $1. Such as answering this question. That's because ta

A smile. Note that there are a lot of things many people are willing to do for free but wouldn't do for $1. Such as answering this question. That's because taking money for it interferes with the personal satisfaction of an altruistic or community-building or socially responsible act.