A CFL Lightbulb will provide you with 75% energy efficiency.

Compact fluorescent lamps (CFLs) use less electricity than your normal incancesdents and can pay for themselves in about nine months. If you purchase an Energy Star Qualified CFL, it will use about one-fourth the amount of energy and lasts about ten times longer than your incandescent.

CFL Bulbs are also able to be recycled, and many retailers will recycle them for you at no cost.

CFL bulbs - energy savers
Energy Saver: