I've always thought that someone could make a bundle renting out different flavors of power supplies for laptops around university campuses, although you'd have to figure a way to gaurd against people simply renting and stealing them. Heck, you might even be able to sell them at retail and make a bundle (students frequently end up in a bind an go to great lengths to find a power supply to borrow... sometimes the right supply can't be found for borrow).