For about a year now I've been reading S. M. Stirling's novels of the Change. The basic idea is that a strange calamity overtakes the world, rendering all explosives, firearms, batteries, and electric energy (even steam, actually) useless. It's basically a device to throw the world into pre-17th century conditions. I've been interested because of my tendency toward apocalypticism (worries about peak oil, climate change, financial collapse) and the fact that I have no valuable skills.
But, it seems like my worries here have turned into a skill: I've compiled a detailed set of plans for building defenses (fortifying part of the town and colleges) as well as alliances with the Mennonites and other farms. Really, the key is a three-fold plan: shelter, food, defense. The defense has been hard. Some people think we can rely on guns. I think that's not useful--bullet supplies are not endless.
Fortunately, I've convinced the college where I teach to begin mandatory training for all the students, 2 hours a day, every day.
At first people thought that only the athletes needed to be trained in archery, sword fighting, and shield work and that the rest of the students could focus on crafting bows and arrows as well as making chain mail and armor. It seemed like a division of labor would be more efficient. Yet, that would render some basically defenseless against the others. The armed students would be able to exert undue influence. So we agreed that everyone would receive proper military training and then people could focus on wood work, metallurgy, etc.
I hope that after a few months of this we can separate out some of the really skilled warriors and train them to be ninjas. That will give us a heavy advantage in the years after the crash, as all hell is breaking loose.
Well, that and my meticulous plans.