There was a flurry of stories some months back about rogue programs or hackers activating webcams that were external or built-in on desktop and Mac laptops. The stories left a lot of people with a queasy feeling, and recent NSA revelations have also called into question the security of our computers and mobile devices.
Camera Lock (US$2.99, currently 40% off) is an interesting Mac utility that enables you to lock out your camera and refuse access by any app. If the camera was already in use, the video freezes and the green LED starts flashing.
The app operates from the Mac menu bar, and lets you lock or unlock access to the camera. If unlocked, the app alerts you that someone or some app is trying to access the camera. The Camera Lock app can be launched at login, and there is a log that shows recent activity.