Just out of curiosity...
I've got an old (1950) house, most of the light fixtures are just controlled with a simple switch on the line. No neutral wire, no ground wire, just a single hot coming up into the box, into a switch, and then a single wire up and out to the ceiling.
I've just discovered one of these switch boxes is not grounded at all, not only is there no ground wire in the box, but, the box itself isn't grounded to anything. Tested via multimeter connecting the bare hot to the metal box, and the needle didn't budge.
I do have an outlet fairly close to this switch, however, which does have ground. Could I, in theory, fish a ground wire down from the ungrounded box to this outlet and make a pigtail connection to that outlet's ground? I am guessing it's not according-to-Hoyle best practice, but, better than nothing, right?