AngelList

Thumb (aka Opinionaided) is a utility-based social network that helps people get instant opinions. The company and service has been featured by CNN, TechCrunch, VentureBeat, Ad Week, and many others as one of the first social networks with a clear value proposition. The service is growing quickly, is regularly compared to a structured version of Twitter, and has engagement numbers on par with Facebook and Angry Birds. Try it yourself at http://www.thumb.it.