We always wanted to do a cooking show, so here goes. Can you guess what the following foods have in common? There's instant soup, hot instant cereal, tea, instant coffee (decaf or regular), gelatin and baby food. Give up? They all need hot water before they can be consumed. And, if you were thinking of heating water on the stove to accomplish your cooking project, we've got some money-saving news for you. Price a hot-water dispenser. They hold about a third of a gallon of water at a constant temperature of 190?F, and cost about eight cents a day to operate. That's about a third of the cost that it takes to get the same job done on an electric stove. And it's about the same cost as heating in a microwave. And that's the On The House tip for today.