Localise
Nice and easy management of languages and translation files.
Site, Administrator, Installation Languages Create, Edit, Delete Languages Create, Edit, Delete, Publish, Unpublish, Checkin, Checkout Translation Files Show Translation Progress for each file and language Automatically create missing Translation Files Create Language Installation Archives
This component works on the language translation files of your Joomla installation - it will not work without reading, writing and renaming rights on the language directories and files.
YOU SHOULD MAKE A BACKUP OF YOUR LANGUAGE FILES
http://extensions.joomla.org/extensions/languages/language-edition/17755