WPML http://wpml.org/ (WordPress Multi Language) seems to be exactly what you’re asking for and more than that. It’s not free, but in this case price means quality. For example I’ve used qTranslate in the past, and I can tell you it was accepted mistake not to spend the money on wpml.org instead (qTranslate is free).
The price IMHO isn’t that high compare to the product ($29) and you get it with an unlimited license.
Take a look, I’m sure you’ll agree.
Just to make it clear, I’m not affiliated with them in any form.