Accubattery - Monitor's battery capacity through the use of science
Padbury Clock Screensaver - Minimal screensaver for Mac
BatteryCare - BatteryCare - Application and good practice guide for maintaining and optimizing the battery of the modern laptop
XScreenSaver - XScreenSaver is the standard screen saver collection shipped on most Linux and Unix systems running...
coconutBattery - With coconutBattery you are always aware of your current battery health. It shows you live information about the battery in your Mac and iOS devices (iPhone, iPad)
Really Slick Screensavers - Really Slick contains free 3D OpenGL screensavers.