4 Prong to 3 Prong Dryer Adapter: Amazon®.com
This cord converts a "standard 4-prong dryer outlet" into a 6-15 outlet. This lets me unplug the dryer and plug in a 220-volt cabinet saw. This proved to be far less expensive than to have an electrician install a dedicated 220-volt circuit for a "hobby saw" that is used somewhat less frequently than the dryer.