LEDs are more energy efficient and last far longer than light bulbs. But their color range has been rather limited. A graduate student at Vanderbilt University has discovered that you can paint LEDs with quantum dots . The color produced by the quantum dots, nanocrystals of a precise specific size, can be varied by varying the size of the crystal, but the result is usually one specific wavelength. Michael Bowers at Vanderbilt discovered that crystals of cadmium and selenium that contain either 33 or 34 pairs of atoms are both preferentially formed (thus making mass production easy) and emit a broad-spectrum white light akin to the sun or a standard light bulb.
Another interesting application of quantum dots is for more efficient thermoelectric devices, for example devices to cool our increasingly hot silicon computer chips. Quantum dots allow a greater ratio of thermal to electrical conductivity -- that means more heat pumped while retaining control over the electric current.
Also interesting is infrared paint. It seems to me that infrared-scale quantum dot paint might also be used for passive thermal control.