Last Updated May 20, 2009 1:25 AM EDT
Aerofoil lives in your System Tray and, by default, automatically turns off Aero Glass whenever the laptop is running on battery power. When you plug your laptop back into the wall, Glass goes back on. If you prefer, you can manually toggle Glass from the Aerofoil icon as well.
Aerofoil is sort of like the Vista Battery Saver, which Rick wrote about some time ago. Aerofoil, though, is far, far smaller and more efficient. It's a tiny program that doesn't depend on the .NET Framework. [via ghacks]