Cleverchimp
Cleverchimp: "Introducing Stokemonkey Human Electric Hybrid Drive
Stokemonkey is an electric motor assist kit for Xtracycle Sport Utility Bicycles. Xtracycle gives almost any bike amazing cargo capacity, and Stokemonkey gives you the power to haul it over mountains or swiftly across town."
Rick Langlois pointed me toward this rather expensive electric motor add-on for bikes.
