Originally Posted by JD

1. Command+shift+3 will take a whole screen screenshot.
1a. Command+shift+3 will allow you to "draw" a box on the screen where you want to capture
2. put all 4 fingers on your trackpad and slide them up at the same time like you're extending your fingers. it'll move everything out of the way so you can access your desktop
3. You need to select multiple pictures for the next stuff to work
4. Command+Option+Esc will bring up the force quit prompt