LED bulbs are rapidly becoming mainstream, with prices going down and quality/performance going up. In fact, some cities are replacing over a hundreds of thousands of street lamps with LED models to save energy, increase safety, and reduce maintenance costs.
But that's not all the technology is good for. LEDs use so little power that it's possible to put a battery in the bulb and turn it into a flashlight when power is out. That's what designer Lin Guohui did, and his bulb (which you can see above) is sold by the Museum of Modern Art (MOMA).
I don't think it's a must-have, especially now that most smartphones with a LED camera flash can be used as flashlights, but in some cases it might be a good idea. Having this in an easily accessible lamp would mean you don't need an extra flashlight, and combining these two things does reduce consumption. But only if you really need it and don't already have an alternative.
Works and recharges in any standard E27 or E25 screw-in light fitting. When fully charged, extend the telescopic handle and use it as a flashlight up to 4 hours. It uses just 6 watts of power to produce light equivalent to a 40W incandescent bulb. The LEDs will last up to 60,000 hours. Charge minimum 5 hours.
In any case, it's a good example of how this new technology (well, not literally new - LEDs have been around forever - but new to mainstream lighting applications) can lead to innovation.