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!
Sometimes you and your friends, partners, or relatives get into debates. Sometimes, you can't agree so we like to hear other people's opinions on our thoughts. Post a question, your take, then invite the one person you want to debate or argue with. They put in their take on the question. The public votes on which side they think is right.