Creating a multilingual website is in fact not easy and is unique because totally dependent of content strategy and users navigation expected...
There is huge quantity of themes (free or commercial) and it is impossible (for free) to support all the customizations (menu, flags,...). So dev.xiligroup provides free examples based on twentyten and twentyeleven.
and now famous free Responsive:
Theme's authors and webmasters will find here some tips and tricks. Read also http://wiki.xiligroup.org
If you want to spare time and need professional services, contact us - http://dev.xiligroup.com/?page_id=10