- Command-Control-Shift-3 - Takes a screenshot of the entire screen and saves it to the clipboard.
- Command-Control-Shift-4 - Select an area with the mouse. This grabs a screenshot of the selected area and saves it to the clipboard.
- Command-Control-Shift-4 - Press space, then clicking on a window will take a screenshot of the window and save it to the clipboard.
You can also make it save to a file on the desktop instead of just copying it onto a clipboard buffer by omitting the Control key from all of the above keystroke combinations.