A penny is worth a bit over half a cent. http://www.coinflation.com
Around 2010 or so a Nickel was worth close to 6 cents. I don't think melting them down for profit would've been scalable. You could freeroll them (sock away $1M worth, hope the metal price goes up, if it doesn't you still have the cash value), but I don't think that's efficient either due to the combination of inflation, the relative unlikelihood of big returns on the metal value, and the expenses around acquiring, transporting, and storing/securing the coins.
That's only the newer pennies apparently, is it easy to get old pennies? You might chainload a huge bunch of pennies with a penny sorting machine and that might be worth it at a large enough scale.
A munchkin is someone who follows the letter of the rules of a game while breaking their spirit, someone who wins by exploiting possibilities that others don't see, reject as impossible or unsporting, or just don't believe can possibly work.
If you have done something that everyone around you thought would not work, something that people around you didn't do after they saw it work, please share your experiences. If you tried something and failed or have ideas you want to hear critique of, likewise please share those with us.