When it comes to social media's heavy hitters, there are no bigger players than Facebook or Twitter, right? Not if you're in South Africa. Mobile network Mxit claims to have nearly 10 million users in the country, making it South Africa's most popular social media platform by far, eclipsing Facebook's six million users and Twitter's 1.1 million subscribers. Founded seven years ago by Namibian-born software developer Herman Heunis, Mxit has grown from an instant messaging application into a global mobile social network.