The Hydrolux-4 LED lightbulb is the world's very first liquid cooled bulb. They are incredibly energy-efficient compared to the other bulbs like incandescent or CFL bulbs and its quite affordable as well.
 
The bulbs,  are rated for 35,000 hours of use and only consumes 4W of electricity (compared to a 25W incandescent). This means it'll cost you fuckall. And that's just the right timing because electricity bills will be going up real soon. It's fully dimmable and, unlike other LED lights, cool to the touch, thanks to the oh-so-hardcore liquid cooling. Check out the link for more info. [Eternaleds via Engadget]