I have a MacBook Air which has a built in camera. Is there any simple application (preferably one that comes with Mac OS X) which simply takes a picture and saves it as PNG or JPG?
ImageSnap is another great command line utility for picture taking or video recording from a connected camera (whether it's your iSight camera or a plugged-in camera). It's a handy little application.
Doesn't come pre-installed with OS X but isightcapture supports command-line picture-taking with the built-in (or external) iSight.