Ask HN: What are some good incentive providers for web apps?

I am trying to find an incentive provider that I can integrate with my web application. I want it to work such that every time an action(that I define) is taken, they would get rewarded a certain number of points. I want to give people the ability to convert points to tangible rewards. So far the only two I have found are Tango Card(https://www.tangocard.com/) and I Feel Goods(http://www.ifeelgoods.com/). I was wondering if there are more popular ones used?