A standard first-aid kit is a good start. Next, store an extra supply of all prescribed medications. Rotate these by using the oldest pills first. Missing doses of blood pressure medicine could be life-threatening. If anyone has any allergies (and even if you don't think they do), store some anti-histamine like Benedryl. Stings or other allergins can produce swelling and breathing difficulties that can be very dangerous. This can happen even if you've never had an allergic reaction before. Anti-histamines can save someone's life.

Cooking

While you may run a generator and never need an alternate way to cook, redundancy is a good thing when it comes to survival storage. You can make an alcohol stove out of a cat food can (or tuna or potted meat for that matter). For fuel use gas line HEET in the yellow bottle. For a couple of dollars you have an emergency stove and fuel to run it. Add a sturdy pot-holder (to keep the pot up off of the stove) and you can keep the home fires burning. Nothing cheers the soul like a hot meal.

Store Blankets and Clothes

Unless you live in a warm climate, power outages in the winter can let your house get cold fast. Extra blankets will be a welcome storage item if you ever really need them.

Emergency Lighting

Candles, lanterns and other lighting options are essential. You'll want to store a variety of Emergency Lighting . Oil lamps and lamp oil (get several bottles) are a good choice. Candles are cheap but may be smelly. Don't go TOO cheap here as some candles have been found to have lead in their wicks. Scented candles work fine, but you may be sick of the smell real soon. Some people are sensitive to perfumes also. Best to get good plain white candles.

To run a generator or your vehicle, you may want to store some extra fuel. Store fuel in a special barrel (or even large gas cans) and refresh it often (by pouring it in your car and refilling the gas can). You can store fuel long-term by using a preservative. PRI-G for gasoline, and PRI-D for diesel.

If you lose power during an emergency your house probably won't be as warm as you like it, even with supplemental heat. Make sure you have extra blankets and other bedding on hand. Rolls of plastic and duct tape will allow you to reduce the amount of space you need to heat.

One of the cheapest ways to be prepared for a lot of possibilities is to have building materials, tools and the knowledge available to construct the things you'll need to make as you go. Usually materials are cheap and easy to get, but when you need them in an emergency it may not be so easy. Store them now. Even if you just keep some wood scraps around. You might also keep an eye on Freecycle for unwanted items that may come in handy.

Don't forget to keep books and games around. People get bored quickly (and cranky!) with nothing to keep them occupied.