The list author says: "What you need in your emergency kit depends on what kinds of emergencies you're preparing for. Your car could break down, you could get in an accident, or you could be trapped by bad weather such as flash floods or blizzards. Or you could come upon someone else who needs help. You'll have to decide for your self which scenarios you consider "reasonable" to prepare for.
Imagine yourself in each scenario, and then think about your current emergency kit -- does having it make you feel better? If you've got some small off the shelf kit the answer is probably "not really". Consider adding the items below. A few are expensive, but many can be found for a only a few dollars if you check clearance bins. You also don't need to go out and buy everything at once. Adding things gradually as your budget allows will still leave you better prepared than you were.
You may want to get a backpack to keep it all in so that if you're forced to leave your car you can bring your emergency supplies with you. You should also have a first aid kit but that's a whole topic unto itself."
"This tiny stove would be a great way to boil water or cook food if you get stranded, without all the work of building a camp fire. Test it out and make sure you know how to work it before sticking it in your kit."
"If you get stranded somewhere and need to make a fire (or shelter) a hatchet will be very useful. Also useful if a road is blocked by downed trees. A hatchet isn't ideal for large trees, but at least with this along you'll have the option."
"There are many cheaper flashlights, but few give you the choice between up to two hours of extremely bright light (useful during car repair or first aid) or dim but usable light lasting up to 71 hours. Takes 2 AA batteries"
"This sleeping bag design will retain heat a lot better than the cheap space blankets -- mainly by keeping out the wind. These are a little tougher than the cheapest ones though you'll still have to be careful with it."
"Maybe useful for roadside car repair. If you have a minor accident maybe you can use this to bend things back into place enough to make the car drivable. Or perhaps someone is stuck in their vehicle after an accident and you can use this to pry their door open. If your day really goes bad perhaps this could be a defensive weapon."
"You're not likely to be bothered by animals, but if you break down in the boonies you may feel better having someway to scare them off. May also help against 2-legged animals. Make sure it's not a restricted item in your area."
"Pack extra batteries for all electronic devices. Try to get devices that all use the same battery type if possible so you can share batteries as needed. Lithium batteries have the longest shelf life so they're more likely to work if you need them, even if you don't remember to replace them as often as you should."