There are lots of things I feel others ought to know (because after I knew them I felt I understood the world a lot better than before) but not many fall under procedural knowledge. Computer programming is one thing I really value having learned, mostly for non-procedural reasons (clarifies thinking, adds a large useful set of analogies etc.) which has also proved practically useful (e.g. writing scripts for repetitive things and understanding computer errors).
Another thing I've just recalled: If you run out of gas somewhere you can call a cab and ask the driver to bring a can of gas with him/her (this applies in Iceland at least, YMMV).
There's been a recent heavily upvoted and profusely commented post about things people want to learn. It's close to having so many comments in a single day that it should probably have a part 2.
However, the subject seems to inspire thoughts about what *other* people ought to know, and while that's got a good bit of overlap, it's emotionally rather different.
So, what do you think other people ought to know? Any theories about why they haven't learned it already? Any experience with getting someone else to learn something when it started out as your project rather than theirs, especially if the other person was an adult?