Everyone else seems to have covered anything I was going to post, so I figured I'd just share how I decided what to store for my family (DH, me, and LO on the way), and some of the things we keep stored.
I sat down and thought about 15 meals I actually cook on a regular basis and what I would need on-hand to make them. I came up with an ingredients list, then multiplied it by 2 for a month's supply of items to stock. I like to cook from scratch, but I also included lunch meats, cereals, hamburger buns, peanut butter, canned and powdered soups, and other store-bought items that wouldn't be available in a prolonged emergency situation.
Then I went shopping, and made sure I had at least a 2 month's supply on-hand. Now when I go to the store, I buy items to replace my storage, not because I've actually run out. It's like shopping 2 months in advance...!
We try to eat seasonally anyways, but that includes canning and freezing the in-season produce. We also bought meat in bulk last year (42 lb mix of chicken, pork, and beef, plus sausages and bacon cost us about $120, just fyi), so I consider that to be part of my food storage as well. A fridge-sized upright freezer made this possible for us. By late fall, it's packed with enough meat and veggies (I freeze broccoli, carrots, several types of peppers, pea pods, corn, green beans, and berries) for the next 9-12 months. I also have a supply of home canned pasta sauce, applesauce, peaches, pears, and jams in addition to my staples (flour, sugar, dry milk, honey, oatmeal, pastas, and rice). I also recently learned that you can can butter (http://geocities.com/~y2k-survivor/HOWTOCANBUTTER.html
), so I plan to store some of that as well. And some items that we "store" are just foods that generally have long shelf lives: onions, potatoes, dry beans.
That said, I also store some things I don't use on a regular basis. Our family camps and backpacks, so I bought a few #10 cans of freeze-dried Mountain House meals. I'll scoop out a few servings before a trip, but I definitely don't use them every day. Same for the powdered milk.
Make sure you keep some goodies on-hand too! Even if you don't normally make instant pudding, for example, it might be nice to have some sweets during a stressful time.
We have well water, but no hand pump yet, so I have 25 gallons of water stored in mylar bags from www.beprepared.com
I also have a water filter that I use for backpacking that we can use in a real emergency.
Eventually, I'd like to buy more property and have chickens and dairy goats so that we can be more self-sufficient. Our current zoning restricts us to 3 "pets", and we already have 2 dogs and a cat. I don't think our neighbors would appreciate a goat, anyways.
Hope this helps!