OS X
Save screenshots to a particular folder
defaults write com.apple.screencapture type pdf; killall SystemUIServer
Command-Shift-3: Take a screenshot of the entire desktop
Command-Shift-4: Allows the selection of a specific area
Command-Shift-4-Spacebar: Allows the taking of a screenshot of a selected window
Command-Control-Shift-3: Take a screenshot of the screen, and save it to the clipboard