Haven't done anything with em yet but I have lots! Going to roll up the rotten ones I think. Do you know if a rotten penny will go thru a home type rolling machine? as long as its not bent up to bad?
Just clean them up and put'em in the counter at the grocery store.
I just wash the coins a bit and run them through the counter at the grocery store to purchase new batteries or accessories. Be careful with the really bad coins. They can jam the machine.
If it's not totally rotten - hit the soda machine. Sometimes you need to give it a little spin when you put it in. I've even hammered some back into shape that it took. Once it goes in.... hit the coin return and out come nice clean coins. Magic.