Charger Alarm by Aitchehtee is a free app for BlackBerry that sounds an alarm when the power gets disconnected. This makes charging in public a bit easier as you’ll hear a loud alarm when someone disconnects the device.
Charging in public has become pretty common ever since phones started getting more powerful and drawing more power. Also the whole industry is on micro USB, making it easier to borrow a charger should you need additional juice mid-day. It like the thinking behind this app, it’s a simple elegant solution to a pesky problem.