Goodness the comments and questions are coming thick and fast!
Here's another issue that's serious: water.
My husband and I have gone back and forth and back and forth on this issue, because we have a problem. We're in the country, yes. We have a well, yes. Our well is powered by an electric pump, yes. So why not look for a manual alternative to pump the water in the event of a power failure?
We can't, because any mechanical solution is light years beyond our budget. We've looked into solar and wind. Both would cost just short of $20,000 because - drum roll please - our well is 610 feet deep.
This means that well buckets, handpumps, or just about anything else is totally out of the question unless we're prepared to spend a small fortune. We can't afford to buy gold - how the hell are we supposed to afford a windmill?
So we're going to look into a roof-runoff storage system.
Others who have shallower wells could try well buckets (a reader suggested the Lehman's version) or an old-fashioned hand pump.
For those without wells, I'd suggest water purification tablets or at least bleach, as well as a water filter (perhaps ceramic filters or a drip filter). This assumes you can obtain water, of course, however unclean.
Never hurts to have as much potable water stored as you have room for, of course.