wabrandsma sends this article from New Scientist: Hong Kong's mass protest is networked. Activists are relying on a free app that can send messages without any cellphone connection. Since the pro-democracy protests turned ugly over the weekend, many worry that the Chinese government would block local phone networks. In response, activists have turned to the FireChat app to send supportive messages and share the latest news. On Sunday alone, the app was downloaded more than 100,000 times in Hong Kong, its developers said. FireChat relies on "mesh networking," a technique that allows data to zip directly from one phone to another via Wi-Fi or Bluetooth. Ordinarily, if two people want to communicate this way, they need to be fairly close together. But as more people join in, the network grows and messages can travel further. Mesh networks can be useful for people who are caught in natural disasters or, like those in Hong Kong, protesting under tricky conditions. FireChat came in handy for protesters in Taiwan and Iraq this year."