Great contest. I replied to John Searles very complete answer with my answer, and one that he seems to have missed:

Absolutely fabulous answer! One of my favorite things about steem is the ability to incentivize behaviors - actifit, which you mentioned is my favorite example of this.

But my favorite application is Utopian.io. It uses the incentivization powers of the steem blockchain to reward open source development. I believe this give us a clear view to the society of the future - where the inflation rate goes to fund people working to better society in an open way.

Keep up the great work Dan! (and I am apparently on my wife's laptop haha)