These Forever Lights ($18.95) do just that. Using LEDs, these holiday light strings have no filament to burn out and will last for about 200,000 hours. Even better, they use almost 80 percent less electricity than incandescent lights. If one bulb goes out (after about 20 years!), the rest stay lit. The Forever Lights can be hung both indoors and outdoors and are virtually unbreakable.