Is there something like this, for "guerrilla" situations? An open source DIY project, a Raspberry PI image, and some kind of WiMAX antenna/WiFi AP combo to give

Is there something like this, for "guerrilla" situations? An open source DIY project, a Raspberry PI image, and some kind of WiMAX antenna/WiFi AP combo to give internet access to a wide area in emergency situations. I have no experience with that field but I think that would be really neat, for people in unstable countries where internet is blocked, or inaccessible. A plug and play, ghetto way of restoring internet access on the go, when all you have is a crappy, flaky and possibly filtered internet connection.