My favorite kinds of household gadgets are those that preemptively solve problems: like hooks by the door that keep you from having to search yesterday's jean pockets for the car keys, or the dishwasher magnet that tells you if its contents are dirty or clean. The Cool Tools blog features a similar problem-solver: the double toilet paper roll holder. You don't want to get caught with your pants down and an inadequate length of TP; this thing makes sure you've always got a spare roll on hand. It'll also keep your guests from canvassing your bathroom cabinets looking for replacement roll, too. The Double Paper Holder will only set you back $17.
Double Paper Holder [Cool Tools]