They might not make you rich, but they can be a fun way to earn some extra cash or gift cards. As for using your computer's processing power, companies like Honeygain and Salad allow you to earn money by sharing your unused internet bandwidth or letting your computer run background processes. Regarding smartphones, they can be used for some of these tasks, but generally, they’re not as efficient as computers. The concept of money games for cash app is popular, and you can find various apps that reward you for playing and completing small tasks. It’s pretty passive, which is nice.