Sharing screen grabs and screencasts is a great way to show someone exactly how to do something with their Macs. You’ve got several choices for screencast software (here’s a list of posts in our screencast category), but snapping a simple screen grab is much simpler.

Using Apple’s Grab application you have a few options:

1. Shift + Command + 3 produces a snapshot of the whole screen
2. Shift + Command + 4 produces a crosshair that you can drag over a specific area of your screen
3. Shift + Command + 4 followed by the space bar turns the crosshair into a camera

Number three will let you grab a single window. The problem is that it includes that window’s shadow, which you might not want. Fortunately, MacOSXHints has described how to exclude the shadow. A single line typed in the Terminal will get the job done.

That’s great and all, but for some real fun, take a screenshot of a collegue’s desktop, move all his desktop icons onto his hard drive, set your screenshot as the desktop image and feign ignorace while he clicks furiously on his “icons.” You’re welcome.

[Macosxhints]