Like duct tape, aluminum foil makes the list because of the seemingly endless array of ways it can be used. The nearly 100-year-old product is lightweight, durable and even recyclable in the event there's much of Mother Earth to be saved. You can use foil to wrap and cook food, make a funnel or even sharpen knives (just fold a sheet of foil several times and cut through it with the knife to sharpen the blade.) You can use it to warm up a room by wrapping a piece of plywood in foil and stowing it behind a radiator to reflect heat; or tape the foil to a window, shiny side out, to keep the sun out. For well-used power generators, a couple foil scraps will serve as a tool for rust and corrosion removal [sources: Urban Survival Site, Stimpson].