Contra is a slick app for voicing your most honest opinions. It's pretty simple; you pose a two-sided question and get thoughtful responses and votes from people all around the world. Be careful though: it gets suuuuppper addicting because of the debate mechanism. I've personally spent a few too many hours on it, just trying to prove my point!
UFC for debates. We are the only online platform for live video debate tournaments, which feature eloquent debaters, credible judges and awesome prizes.