make emacs give an accounting of certain things

[Harry Putnam]

This may sound a little silly or worse yet, be a little silly,
although I think people would find it usefull at times:

I suspect this is already possible, or something close:
I'd like to extract from emacs a list of various things I have set.

For example: I have numererous `skeletons' defined, enough, so that I
forget the ones that fall into disuse for a time. And I have to check
to see what I have defined.  One way is to name them all with certain
prefix like `sk-something', then M-x sk-<spc> will do it with
completion.

But over time one uses all kinds of odd names.

I wondered if there is some way to make emacs be the accountant
instead of me?

Some command that will show a buffer of all skeletons, or defuns, etc
found in .site-start.el or emacs.  One could quickly use M-x occur to
find those matching regex.