OSXDaily has put together 10 commands you can use in the Terminal app to customize how Mac OS X looks and works. These commands are called Defaults Write commands because they alter the default settings of OS X. They are of course reversible, and the list shows the commands you need to type in the Terminal, as well as how to return it to Apple’s default settings.
Some of the commands include: Always Show Hidden Files in the Finder, Speed Up Mission Control Animations, Change Where Screen Shots Are Saved To, and Show System Info at the Login Screen.