I'm happy to present you the public version of a plugin that we have used internally a lot. The On Page Translator lets the administrator of a nopCommerce site edit the language resources directly from the front end. It's not only useful to translate a site, but also to do the small daily edits of your web copy. It's quick and easy to use.
Let us know what you think. And if you are interested, try the code NEWSTUFF16 to get one of a few copies with a 50% discount.
On Page Translator Plugin from nopStuff
Here's a demo video.