Proposal: A TIL: Today I Learned... Share your pro tips! category.
The idea is as follows: You've just understood something that wasn't obvious to you and may be useful to others (even if you think it could be wellknown among long timers), then why not let others benefit from a piece of wisdom?
This includes in particular all the wellknown-but-never-shared tips and tricks.
TODO: Rephrase the above to be inclusive to all levels of knowledge maybe?