Developer website: B-L-A-C-K-O-P
BlackenedPixels is an improved version of the "black screen" ScreenSaver. In addition to making your displays black, BlackenedPixels also trims the brightness control all the way down, allowing applications to run normally, but without the power consumption (and heat etc) normally associated with screensaver operation.
Version 1.002: Fixes problems with multi-monitor displays and non-portables.
Mac OS X 10.4 or later