Try this little joke on your family, friends, or co-workers: Use the Mac OS X Grab utility to take a snapshot of your Desktop with a number of windows open (or an error dialogue box with an OK or Close button), and then save the image to your Pictures folder. Select the image as your Desktop background, and watch others go crazy trying to click those windows! For your archenemy, try the same trick on his Mac! Arrange a slightly embarrassing Desktop on his computer, specify it as the background, and sit back while the fun begins. (Perhaps a Web browser open to a somewhat unusual Web site?)