Click was developed to help you make screenshots. Although standard shortcuts prevent you from making screenshots while watching a DVD movie, this is not a problem with Click (use VLC, not Apple's DVD Player, if checkerboard pattern seen while playing DVD). You can take a screenshot manually by pressing Option-Command keys and also select automatic operation where a screenshot is taken periodically (1 second - 10 minutes). You can select whether or not you want to hear a shutter click when screenshots are taken. Control Panel's location and settings (except for Automatic Screenshot checkbox checked setting) are saved between sessions.
Note: Now requires OS X 10.7 or later.