So far I've seen Food, water, trading items, and all sorts of things like that mentioned. But if you're talking about a long term situation, bottom line is all those nice power tools that everyone has sitting around are going to be great canoe anchors. Lots of folks have a hammer and screwdrivers, but how many have a decent hand saw, axe, bow saw, hatchet, and so on? And how many folks can drill a hole in something with no power? I don't see too many hand drills anymore. Or bit braces.
How many of us have a good quality knife sharpening setup? Knives are invaluable tools, as long as they're sharp. As soon as they get dull, they're not worth much.
And then if you have enough basic hand tools, do you have hardware enough to make them useful? A few pounds of nails could go a long way in putting together or repairing a decent shelter. A couple boxes of screws would work for many things. Rope, cord, string, that sort of thing are extremely useful. A couple rolls of plastic sheet don't take up too much room, but they can be worth their weight in gold in a situation like that. If you're in a camper, and you get a hole in the roof, that plastic can make a big difference. Tarps too.
Basic mechanical tools would allow you to salvage items useful for other purposes than their original. All sorts of things you can use to make something else if you can get them apart.
Just some food for thought.