Screen Shot Format

Apple’s Cocoa Development mailing list archives contain an interesting snippet that explains how to change the default screenshot (command-shift-3 and -4) format from TIFF to JPEG, PICT or PNG. The original article can be seen here (read the dialog box for the username and password), but it’s basically a one-line terminal command:
defaults write NSGlobalDomain AppleScreenShotFormat imageFormat

Replace imageFormat with one of JPEG, TIFF, PNG, or PICT to change the format of the screenshot