Link to site: http://www.tricider.com/
I am always on the look out for different ideas on ways to engage and involve my students both in and outside the class room. Social media can be a great way to do this and I have found Google + communities have provided a popular way to continue a class conversation beyond the end of the lesson.
However for those who don't use Google+ or want something that they don't have to sign into use, Tricider could be the tool that suits you. Through this site you can, ask a question get people to contribute answers and then they can vote on the answers they like the best.
You start by posting a question, having posted a question you add a couple of ideas. Ideas can be voted on, the most popular idea appearing at the top of the page. For each idea, pros and cons can be added.
You can share you Tricider via social media or a link.You can also set a time limit for your Tricider, the default is 14 days, once the vote is closed you can share the results with the participants.
I could see this being a good way to encourage students to debate a key question or idea, whilst offering their opinions and considering pros and cons, then vote on the best ideas.
Here is my video guide.