Shorten URL to Clipboard is a free and easy to use OS X service that will help you to quickly shorten URLs and send them to the system's clipboard.

Installation:
· To install it, simply drag it to your Home → Library → Services folder (first creating that folder if necessary). It will then be available in most applications.
· To use it, choose “Shorten URL” from the Services menu in the Application menu (the menu just to the right of the Apple menu, carrying the name of the current application).
· To remove it, take it out of the Home → Library → Services folder, e.g., to the Trash.