OS X screen grab keyboard shortcut

According to this page:

“Command-Shift-3 shortcut for taking a screen capture of your entire screen”

Useful, but even better:

“Command-Shift-4, … gives you a crosshair cursor so you can choose which area of the screen you want to capture.”

That is really great. There are a couple of other options for saving the screen grab to the clipboard instead of the desktop.