Being given to unnecessary worrying I've even wasted some chunk of my life about turning into a survivalist nut. But after talking to some of my friends, the things that I've most thought about doing are pretty reasonable. My near term goals are to attach my bookshelves to the wall, put together an emergency preparedness pack, and to store 1 to 2 weeks of water and 2 to 4 weeks of food. The base FEMA recommendations are 3-4 days of food and water, though they did recommend up to 2 weeks, so these short term goals are perfectly reasonable.
Some of my longer terms goals are also heavily influenced by my worries for the future. For instance pushing myself further toward biology research is partially to avoid problems with too many programmer jobs being outsourced, as well as if civilization is going to be crumbling soon, it'd be really nice to be able to bioengineer some microbes to make some of my medications. (Though admitting to this probably marks me as being further off on the wacky survivalist camp).
On a more amusing note when I got home I discovered the camp stove I bought can run on biodiesel.