As a volunteer Federal disaster medical responder (think Katrina), we always have our go bags packed and ready for deployment. That includes bag, pad, clothing, a couple days worth of food and water, and basic essentials. I have a 70 L. backpack that is nearly good-to-go as well (put the pad and bag in as I head out the door).
In addition, for home use during a disaster, I tend to stockpile freeze dried food, canister fuel, as well as 10 gallons of water in gallon jugs. The American Red Cross web site has a decent list of what every family should have in the basement in the event of a disaster. The first things to go during an earthquake, hurricane, or nuke attack are utilities, cell phones, and water--so plan for that, and have a battery powered short wave radio on hand, and plenty of batteries for all purposes.
And as a good ol' Montana boy, I have both a pistol and carbine that use .357 mags, and I have several boxes of ammo in a safe place. I also keep $1000 in various denominations locked up. Then there's the habit of keeping the 4Runner full of gas all the time. For my prescription drugs, I get a year's worth at a time, so that there's little chance of running out.
While none of this relates to lightweight anything, it ALL relates to being prepared. Like we do when we pack for a backpack trip.