By now most of us have swapped our incandescent light bulbs for compact fluorescents or CFLs. I know I have, and have dramaticaly lowered my electric bills as a result.
The next wave of engery savings is LED or light emitting diodes, offering energy savings versus CFLs on the same scale as CFLs versus incandescents.
Initial fixture costs may be higher for some LED lighting solutions than for comparable incandescent and fluorescent lighting solutions. But initial fixture cost does not account for the total cost of owning, operating, and maintaining a lighting system. Because of their long useful life, LED lighting fixtures avoid the maintenance and materials costs which multiple relampings of incandescent fixtures require over tens of thousands of hours of operation. And because LEDs consume far less energy, annual power costs can be reduced by up to 80%.. The total cost of LED lighting systems, therefore, can be significantly lower than conventional systems. In fact, payback on LED lighting solutions can often be realized in less than three years.
http://www.ledlightingexplained.com/led-lighting-myths/