I think in future, if the citys will grow and grow. There is a big possibility for a riot or some kind of violence everywhere. You can see it today, it´s maybe a football game or a demonstration with a lot of angry people. so they walking in bigger croweds than today and start to fight. In this moment you could use the Ushahidi platform to alert or to get alert. If everybody do this noone can become part of this riot without fault!