What do I do with millions of odd sized nuts, bolts, screws, stak-ons and other misc electrical supplies?

Countless times I have gone looking for a screw or some such thing through cans filled with Miscellaneous stuff that either I kept or got at an auction or sometimes who knows where I got it from, and been delighted when I found a match to what I needed. You never know when some long left over part is going to be just what you need. And even though it takes time to sort through all the stuff, it takes even more time (and now cost with gas being so high) to run to a store and try to find it there. Sort out the bigger stuff from the smaller and categorize it into general areas, like screws for metal, and screws for wood, welding stuff and such. You don't need a separate storage bin for everything, just a general one that can speed up the looking process. Let your friends know that you have a supply of whatever and the next time anybody needs that weird metric connector from a VW they might just find it. Once you throw it out its gone for good. Keeping leftover junk might appear to be cluttered and disorganized but throwing everything away today and then buying it over again tomorrow is truly wasteful. So this is a different form of recycling, but one that is just as valid. Throw out stuff that is really junk, but keep the rest for that time when you might just have the ideal thing already on hand.

Post it on craigslist. If I lived near you I'd pay money for it so I'm sure there is someone, or several if there is literally a ton, who would take it off your hands for cash.

My father also has a large assortment of miscellaneous supplies. I guess they just lived in a generation of "waste not, want not". That being said, I'm assuming you don't share the same interest in keeping these items and using them when needed? If not, there are many ways of managing such a collection, and perhaps having a large sale is the way to go. Advertising it ahead of time, using as many outlets as possible to spread the word, and including as much of a list or photos will draw more interested buyers. I would do that before scrapping it all. There is a significant value in all these parts and its likely why your father saved them and the same reason why you'll probably get A LOT of interest if you sell them.

Depending on where you live there might be a hackerspace/hobby-club who would love to take it off your hands to have around "just in case"

Perhaps the art teacher at your local Jr. High or High School would be interested in them as materials for an art piece? Be sure to ask first - don't just show up with a box :-)