Thanks for the great suggestions everyone. To follow up, here's what I did as a result of this thread:
-Put batteries back in my smoke detector
-Backed up all of my data (hadn't done this for many months)
-Got a small swiss army knife and put it on my keychain (already been useful)
-Looked at a few fire extinguishers to make sure I knew how to use them
-Put some useful things in my messenger bag (kleenex, pencil and paper) - I'll probably try to keep adding things to my bag as I think of them, since I almost always have it with me
All of the car-related suggestions seemed like good ones, but weren't applicable since I don't own a car. Some other suggestions were good but required more time than I was willing to put in right now, or weren't applicable for other reasons.
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.
To any future monthly posters of SQ threads, please remember to add the "stupid_questions" tag.