simple battery power monitor for laptops with ACPI

 fdpowermon is a simple perl script that installs an icon in a system
 tray compatible with the freedesktop.org specification.
 .
 Every three seconds, fdpowermon calls acpi to find out what the current
 battery level is. It will set the output of the acpi command as a
 tooltip text, and will update the used icon as appropriate.
 .
 It has no other 'features' like trying to manage your processor speed
 or display backlight for you, preferring to let other subsystems (or
 none at all) be in charge of that.