Finding UNassigned keys / keymap utility?

One utility that would be handy for customizing the interface to one’s preferences would be an easily accessible list of UNassigned keys.

Does such a thing exist?

Similarly, a simple (dynamic) ALPHABETICAL list would also be useful. Keys and combos on the left, then columns for the different modes.

(posted to RCS)

I’m going to bump my own question: ^^^

tl:dr: QUICK way to find out which keys are unassigned?