Answer quick surveys and earn Google Play credit with Google Opinion Rewards, an app created by the Google Surveys team.
Getting started is easy. Download the app and answer basic questions about yourself. They'll then send you surveys around once a week, although it may be more or less frequent. You'll get a notification on your phone when a short and relevant survey is ready for you, and can receive up to $1.00 in Play credit for completing it. Questions can range from, "Which logo is best?" and "Which promotion is most compelling?" to "When do you plan on traveling next?"