Something from the category of useful things hiding in emacs… Suppose you are looking for the variable that holds a certain value. How to find it?
So, for example, finding all variables that hold your e-mail address:
M-x apropos-value RET firstname.lastname@example.org RET
and you'll get all the matches in the
*Apropos*-buffer. HT: Stephen
Also check the various other
M-x apropos-... commands, they all help you
find useful information if you can remember a word. Except for…
M-x apropos-zippy… eh?