If you are one of those who is very concerned about the battery status of your MacBook (Pro / Air), the Watts software developed by Binary Tricks is highly recommended.
Watts works as a battery recalibration assistant, alerting the user when the process has to be done in order to keep them at maximum efficiency. In the main window of the application (or in the menu bar of the operating system), it is possible to check all the details about the state of your battery.
Compatible with Mac OS X 10.5 or higher, Watts is a universal torque and costs $ 7. Anyone can test it (DMG; 4MB) for free and completely for 60 days, before hitting the hammer.
(via The Loop)