I have given this some thought actually (well, who hasn't?).
I think Tightwad has got it pretty close. The monster (Federal gov.) is too big to just let thousands of us wander off into the wilderness and build tee-pees (unless you get out really fast)and start armed communes. Put, we never really know do we?
Back to what to do...
I figure the following would help no matter how bad the situation becomes:
1. eliminate all debt, except those absoulutely necessary (ie-mortgage). Stop buying new cars, trucks, etc. and learn to drive what meets your needs. Forget new DVD players, stereo's, etc. forget the toys and go enjoy developing skills that will really help you some day-heck go excercise!
2. Stop 'collecting' knives (right-I know this one may be tough-sorry

). Have several good blades that meet any expected need in duplicate at least. USE THEM, you must know how to get the best out of every blade; by limiting the number available to 'play with' you insure that when\if the time comes you won't stumble over which one to take and which to leave. Make sure this covers every mature family member and your spouse. Get a good sharpening system or stone and make sure everyone knows how to use it. Unfortunately, you as the head of househould (I am assuming)may not always be there. Don't forget a good axe, hatchet, machete, files, hones, fire strikes, and spare parts if necessary.
3. Stop collecting Firearms. Jeff Coopers concept of a Scout rifle (one weapon=many applications) seems very sound to me. Get a good rifle-and SHOOT IT. Limit your personal weapons to a few rifles in the same caliber. A pistol for every mature family member in the same caliber. A .22 pistol and at least one .22 rifle. And at least one good 12 gauge shotgun setup for hunting\defense. This limits your need for ammo to only four calibers. My personal setup includes: .30/06, .45ACP, .22, 12 gauge, but should use what is comfortable or affordable for you. Make sure each weapon has a proper cleaning and maintenance kit. Next take these weapons somewhere and SHOOT THEM!!! Too many weapons lay around, and their owners never learn how to properly care, feed, and shoot them-this has the potential for disaster. Consider a reloading setup. Relatively cheap, and effective way to cut ammo costs. Also if the crisis gets to the point where you have no local gun shop to run to, you will need to know the skills necessary to reload.
4. If you want to stockpile something-stockpile GOLD. Always seems to have some value, relatively easy to store or move and easily converted back to 'green backs' if needed.
5. Keep one vehicle totally road worthy and full of gas at all times (within reason

). Because "you never know". Have emergency plans and kits ready to toss into this vehicle at a moments notice. You may have to run and grab the wife and kids and head for the hills.....or out of the hills...think of the forest fires burning right now.
6. Consider-NO-TAKE-first aid classes and CPR at your local community school or college. This is one activity you will never regret and will always use.......
Everything else boils down to your own personal emergency plan. How far you take it is up to you. Where you live, and the conditions you will most likely encounter will determine what your storage needs etc. will be.
Keep it realistic and dare I say 'fun'. Make it a family activity. It will give you an excuse to take the family out for a day at the range, or camping, or for a hike instead of renting a movie and sitting in front of the BOX-this to me is quality time, and will serve them the rest of their lives.
Mongrel