Hashfootery
Created in the very early days of Twitter, Hashfootery used the social media platform to create an easy-to-enter competition, where anyone can tweet a prediction to selected matches using our composite match hashtag. The competition includes a league, as well as knock-out competitions for followers, and special competitions for World Cups and European Championships. It has even spawned a Super Bowl stand-alone prediction game, and Cricket Predictery - a spin-off for the Ashes. We've been working on a Wimbledon version for a while now.... Follow us on twitter.
Predictery
Following the success of Hashfootery, we built an Oscars prediction game in 2011 - Predictery. Entries are via twitter or via email, and we crowdsource prizes (a DVD collection) every year. Follow @predictery on twitter.