We toss all our pennies into an old coffee can that doubles as a door stop for the office door that likes to slam shut with the slightest breeze.
A few months ago our 6 year old neighbor twins knocked at the door with a baggie in hand and asked if we had any pennies we'd like to donate to a penny drive the school was having to benefit a local child with some debilitating disease.
I led them to the office and hefted the coffee can into their hands. Their faces were so comical! They got it to school the next day and their class won the school penny drive. I don't know what the total amount was that the school kids raised for the disabled child, but it was such a perfect thing to do with a door stop that we had no plans for.