Over Christmas I saw (bits and pieces of) a program on the History channel on survival after societal collapse. The program focused mostly on the resources that are required to keep you alive (food, water), where you can find those after the most obvious supplies are exhausted, and what happens physiologically when you're denied food and water for an extended period of time and how to deal with those effects.
As I've been listening and reading about the Haiti earthquake and its aftermath, I'm struck by the focus on food while forgetting about water. You can survive much longer without food than you can without water, yet we think of sending food first. In my ward there's a project (announced just before the Haiti quake) to put together 72 hour kits. It's a great idea, but again, the 72 hour kit is mostly food for three days, not water. Really, I'd think it most important to have a filter or iodine tablets in an emergency. I guess that means I should put together my own 72 hour kit with some water and some iodine for an emergency.