UnPlugged is an application that notifies you when the power cord of the MacBook is unplugged or plugged back in. It also notifies you in regular steps about your batteries capacity while you run on battery or while you charge your battery.
Notifications are done using the Notification Center, Growl or with a built in notification window.
UnPlugged stays completely invisible while monitoring your power plug. Only a small Menu Item is visible, showing the current battery status.