Windows: When you're away from an outlet and flying on battery power alone, keeping an eye on how much juice your laptop has is critical. BattCursor makes it easy to track how much power you have left.
BattCursor has multiple ways of helping you keep track of your battery life. The method for which it was named is, as seen here, turning the cursor into a floating battery meter. As you run low the cursor gives both the percentage and a visual indicator.
If you're using the Aero Glass style you can also set BattCursor to tint the title bars of windows. When your battery is full or nearly full the title bars are their regular blue colour. As you run out of batteries they begin to shift through a spectrum of warning colours until the title bars are red. You can also set BattCursor to disable Aero Glass once your battery is running low to squeeze a little more life out of the battery by not using a resource-heavy style.
If you have a favourite program for keeping an eye on laptop battery life—or even milking your battery for more time—let's hear about it in the comments. BattCursor is freeware and requires Windows Vista or higher.