SlimBatteryMonitor is a space-efficient replacement power gauge for your Mac OS X menu bar. It monitors both laptop batteries and many UPS batteries. You can select different views for when powered, charging or on battery... even instruct SlimBatteryMonitor to automatically hide itself in some circumstances (e.g. while fully charged).
A graphical icon shows the power remaining, and can be accompanied by a text description (battery charge in percent, or time remaining). Colours indicate whether the system is fully charged, charging or on battery. In some cases, SlimBatteryMonitor can be 70% slimmer than Apple's system meter... With SlimBatteryMonitor you'll have room for other important menu bar items.
RIDOGI It's great to be able to have the battery icon turn red when you're running low -- really catches the eye so you don't get caught off guard. The only thing I'd like to see in it is the ability to switch between the energy saver modes as in Apple's standard menu bar icon. (Version 1.4)
MACUPDATE109 Elegant. Light. Saves menu bar space compared to Apple's battery thing. Doesn't gobble up resources. Doesn't do anything unnecessary like graphs.
FREAKYFINK I much prefer SlimBatteryMonitor over Apple's manubar battery icon. I'd love to see a universal version of this for my MacBook Pro! (Version 1.3)
AKROBAT I was looking for something like this but seemed only to find widgets.
This developer however has not followed everyone else in developing similar widgets but has made a proper replacement for the oh so ugly and space hogging apple battery icon.