Without turning my head an inch, I count seven things running on battery power on my desk. And undoubtedly the easiest thing to do will be to dump the used nickel-cadmium into the garbage can once it's used up. Batteries can unlock, compute, record, play, and call. But they can also pollute lakes, contribute to heavy metals, expose water to acid, and much more. Get educated on the dos and don'ts of battery recycling, and keep an extra recycling bin just for household batteries alongside your aluminum and plastics bins. Drop them off somewhere nearby, and save the earth.