http://www.sciencenews.org/20031004/bob9.asp
Lightbulbs and a radiation law may never be the same
"...bulbs with photonic-crystal filaments might convert as much as 60 percent of their power to visible-light output. In other words, 6-, 9-, and 15-watt photonic-crystal bulbs would produce more light than today's 40-, 60-, and 100-watt bulbs do."