Localise

com_localise will let users/translators edit language files and create various language packs for Joomla!™

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