Does anyone know of an appliance where you can just plug it into the wall and plug anything into the appliance? Basically it would act as a pass-through that c

Does anyone know of an appliance where you can just plug it into the wall and plug anything into the appliance? Basically it would act as a pass-through that could keep track of how much the thing plugged into the wall is costing. It would be nice if you could set a price on it and have it display in $/h or something but that's not necessary, just a running total would be fine. I can handle the watt-to-dollars conversion myself.