beta.cent.co is one of the best dApp out there, and one and only bounty program on Blockchain.
The users can ask questions and pay for bounty, and the other users can answer them for bounty.To this day, I have earned around 40$ ETH. Earning is darn easy. You get paid automatically at 0.001 ETH.
My technique only is upvoting the answers of the people that are answering the questions. I get paid by upvoting. But if you have some ideas of the questions provided, you can participate and answer, in that you will get bigger ETH.
My first payout below last June 19, 2018.