The Heat Helper is an amazingly simple device that saves energy and money. It catches, filters, and redirects the hot air required for drying your clothes, which is normally sent through a vent outdoors. Instead of wasting that energy, that hot air can be used to heat your home in the winter. The Heat Helper pays for itself in lower heating bills in the first year. The creator of The Heat Helper went into the Shark Tank asking for $100k for a 50% share of the company. The sharks loved Lyle, the inventor, and thought the product was very creative, but did not invest.
UPDATE: The Heat Helper is no longer in business.