The Persona.ly plugin that lets you implement Offer Walls in your app. Offer Walls provide the user an opportunity to do something – take a survey, install another app, sign up for a magazine, provide some personal information, etc. In exchange, the user gets rewarded with some form of in-app currency like gems, coins, tokens, credits, etc.
Ad units also supported Rewarded Video; Poll/Survey.
In contrast to many monetization partners, Persona.ly is a “white glove” service — when you register with them, you will get assigned an account manager who will guide you through the setup and other requirements for using this plugin.