qStealthAlert is very small, providing a simple audible alert anytime stealth is dropped. I find this very useful in battlegrounds when combat noise and the chaos of battle may mask when you've been exposed by a dot.
You can disable the sound or replace the .wav file with one of your own choosing (see readme).
New for WoW 3.0.2: Added a new UI panel in Game Menu | Interface | AddOns.

