My kind-of annual post below, with a few changes. I've found that emergency kits make highly-appreciated gifts for friends and relatives, one of those things that are on everyone's to-do list but often don't get done. If the entire kit's too expensive, you can just give a car kit, or get a part (I suggest water and water purification) and upgrade over time.
If people have had kits for a few years then it's also time to consider replacing out the food. If you or someone you know uses camping food, you might switch out the old with the new a year or two before expiration, so you can use the food before it expires.
- Water in plastic jugs, 3 gallons/person
- Chlorine dioxide water-purification pills (purifies 7 gallons) in case water goes bad (after 6 months, assume the water's bad), in case it's leaked away, or in case you need more water.
- Mountain House 72-Hour Emergency Meal Kit, 1 per person
- Mountain Oven Flameless Heating Kit: each kit can be used 5 times and can prepare 2 meals at a time. So 2 kits per two people in a household, but also 2 kits in a single-person household.
- Plastic silverware
- Emergency phone numbers/contact list
- Cheap flashlight/headlamp
- Spare batteries in clear plastic bag so you can see if they've become corroded over time
- Plastic tarp and cord as a rain shelter
- Swiss Army knife
- Emergency shelter, 1 per adult
- Cheap or expensive first aid kit (I went with cheap kits from the local drugstore)
- Cheap rain gear, spare shoes and clothes
- Hand-crank radio/flashlight combination
- Liter water bottle per person (enough to keep you hydrated for a few hours until you can find a water source)
- Water purification tablets (can disinfect murky water from ditches, and you might need to)
- Emergency shelter
- Small amount of long-lasting food (I found tins of honey-roasted peanuts that were good for four years)
- Cheap rain poncho
- Emergency contact list
- Shoes you can walk many miles in, if that's not what you normally wear
- Cheap, tiny flashlight
- wool blanket (additional warmth, or traction under a spinning wheel in the mud or snow)
Lots of great comments here, and a resource link at Making Light. UPDATE: and see the comments below.