This post is inspired by a recent comment thread on my Facebook. I asked people to respond with whether or not they kept fire/lock boxes in their homes for their important documents (mainly to prove to a friend that this is a Thing People Do). It was pretty evenly divided, with slightly more people having them, than not. The interesting pattern I noticed was that almost ALL of my non-rationality community friends DID have them, and almost NONE of my rationality community friends did, and some hadn't even considered it.

This could be because getting a lock box is not an optimal use of time or money, OR it could be because rationalists often overlook the mundane household-y things more than the average person. I'm actually not certain which it is, so am writing this post presenting the case of why you should keep certain emergency items in the hope that either I'll get some interesting points for why you shouldn't prep that I haven't thought of yet, OR will get even better ideas in the comments.

General Case

Many LWers are concerned about x-risks that have a small chance of causing massive damage. We may or may not see this occur in our lifetime. However, there are small problems that occur every 2-3 years or so (extended blackout, being snowed in, etc), and there are mid-sized catastrophes that you might see a couple times in your life (blizzards, hurricanes, etc). It is likely that at least once in your life you will be snowed in your house and the pipes will burst or freeze (or whatever the local equivalent is, if you live in a warmer climate). Having the basic preparations ready for these occurrences is low cost (many minor emergencies require a similar set of preparations), and high payoff. 

Medicine and Hospitality

This category is so minor, you probably don't consider it to be "emergency", but it's still A Thing To Prepare For. It really sucks having to go to the store when you're sick because you don't already have the medicine you need at hand. It's better to keep the basics always available, just in case. You, or a guest, are likely to be grateful that you have these on hand. Even if you personally never get sick, I consider a well-stocked medicine cabinet to be a point of hospitality. If you have people over to your place with any frequency, it is nice to have:

Medicine

• Pain Reliever (ibuprofen, NSAID)
• Zyrtec (Especially if you have cats. Guests might be allergic!)
• Antacids, Chewable Pepto, Gas-X (Especially if you have people over for food)
• Multipurpose contact solution (getting something in your contact without any solution nearby is both rare and awful)
• Neosporin/bandaids (esp. if your cats scratch :P)

Toiletries

• Spare toothbrush (esp. if you might have a multi-day guest)
• Single use disposable toothbrushes (such as Wisp). These are also good to carry with you in your backpack or purse.)
• Pads/tampons (Yes, even if you're a guy. They should be somewhere obvious such as under the sink, so that your guest doesn't need to ask)

Minor Catastrophe Preparation

These are somewhat geography dependent. Adjust for whatever catastrophes are common in your area. There are places where if you don't have 4 wheel drive, you're just not going to be able to leave your house during a snowstorm. There are places where tornadoes or earthquakes are common. There are places where a bad hurricane rolls through every couple years. If you're new to an area, make sure you know what the local "regular" emergency is.

Some of these are a bit of a harder sell, I think. 

• Flashlights (that you can find in the dark)
• Spare batteries
• Candles/Lighter
• Water (ready.gov says one gallon per person per day, and have enough for 3 days)
• Non perishable food (ideally that doesn't need to be cooked, e.g. canned goods)
• Manual can opener
• Fire Extinguisher
• Action: check out ready.gov for the emergencies that are most common for your area, and read their recommendations