Iris is an OS X app that offers up some cool ways to use your iSight. Of course, it takes still photos and videos. That's useful, but Apple's built-in Photo Booth already offers those features. Iris goes a few steps further, offering a time lapse mode, a security mode (using motion-detection), and a webcam mode (for setting up live streaming).
Each mode is highly customizable. In security mode, you can set everything from the sensitivity of the motion detector to the actions Iris will take when it's set off. You can have it sound an alarm or just grab a movie or a stop-motion and email it to you. With time lapse, you can choose the interval for frame capture and playback. An amazing array of video codecs is available for recording, making the movies Iris produces suitable for playing on any screen or device.
The gallery feature ties all these modes together. It saves your shots and your videos in an iPhoto-style display that gives you easy access for exporting, e-mailing, or uploading to Flickr. It also plays nice with AppleTV. The bottom line: If you've used Photo Booth, Iris won't be difficult to learn, despite its large library of features.