Frozen Out

Door locks can freeze in cold weather and break your key if you try to force them open. The old fashion cure was warm water, but what if you're not at home and don't have any warm water nearby? Discount stores, auto parts stores, and even hardware stores sell glycerine you can use for de-icing. Think about where you keep it, however, because if the de-icer is in the glove box of your frozen-shut car, then it won't help you any.
Stock a tube at home in the garage and also in your desk at work. That way whenever your locks freeze up, you'll be able to solve the problem.