What is the best example of an effective government social media / website for public engagement and policy transformation? Why?
I have to say that it will be hard to beat the US White House's "We the People" website at https://wwws.whitehouse.gov/petitions. The site provides all Americans with an opportunity to view existing petitions, write a petition, and vote on petitions. All public input is transparent. If a petition reaches a signature threshold the administration issues a response.