There's a screen capture thing built into the system. To capture the contents of an entire window, while caps lock is down press command-shift-4, and click somewhere in the window. Other screenshot commands: without caps lock, press command-shift-4 to drag the mouse over the area you want selected, or press command-shift-3 to take a shot of the whole screen.
[Edit: I just tried this, and apparently it won't capture anything that extends off the screen. Whoops. Never mind.]
[This message has been edited by Patrick (edited 05-08-2001).]