User Testing is the most popular platform in the industry. Your human insights as a customer is what User Testing is looking for. You will need to record a 20-minute video where you review a certain application or website.
Pay is great, at $10 for every review, and is paid straight into your Paypal. For alternatives, check out these websites: TestingTime, TryMyUi, UserFeel, Enroll, UserZoom, UserLytics, Validately, What Users Do.