The popular (and addictive) Question and Answer Site Quora is not just a hobby. There are many people earning serious money with it.
This guy earns money by including affiliate links into his answers. Read his excellent Quora answer to learn more about this way of earning money with affiliate links.
Watch Gordon Miller at Quora. He is crushing it. He doesn’t earn direct money from Quora but as an investor, he is constantly searching for new deals. Quora gives him deal flow!
This Quora user was invited to become Quora partner. The earnings are quite limited though—but read yourself: