Macs have a pretty good built-in screenshot utility, but it doesn't come packed with a lot of options. One of the problems is the fact you can't easily change the file type or save location of those screenshots. Software blog Addictive Tips shows how to change both with a simple Terminal command.
If you want to change the save location for your screenshots so they don't clutter up your desktop, create a new folder on your hard drive for them and then open up Terminal and type:
defaults write com.apple.screencapture location /your folder path/
If you don't mind the screenshots heading to the desktop but don't like the fact they're always saved in the PNG format, you can change that too. In Terminal, type:
defaults write com.apple.screencapture type FORMAT
Replace FORMAT with BMP, GIF, JPG, PDF, PNG or TIFF. Log out of OS X, then back in, and you changes will take effect right away. It's a simple and effective way to customise the default screenshot utility without having to download a special program to do it.
Change Default Save Location & Format For Screenshots in Mac [Addictive Tips]