Mac OS X trick: Change contextual menus on your Dock
Right-clicking (or Control + clicking) on a Dock icon will bring up a contextual menu with available options for that application or file. This trick will allow you to customize the language of that contextual menu, further personalizing your Mac experience.
For example, when you have Safari open, if you right-click on the Safari icon in your Dock, the contextual menu offers you the options of New Window, Options, Hide, Quit (as well as showing you the current page name). You can change Quit to anything you want, like say, "End" or "Close."