A study out of Cardiff University has shown that Twitter can be used to predict events like riots and that it can be done faster than by police reports. Using the 2011 London Riots as a dataset, they fed 1.6 million tweets through their machine learning algorithm and it identified incidents faster than traditional methods. In each case their system was faster than police receiving on the ground reports.
This isn't quite the Oracle of Delphi yet but one can imagine that a behavioral analysis placed on top of this detection system could have some real predictive power.
via The Verge