Coworker went to Japan recently and got a local to guide and translate for free. The local did it so that they could practice their (already perfect) English. Coworker gets a free guide/translator, local gets exposure to idioms and accent. Win, meet win.
As soon as she told me about this, I had the genius idea to create a web site connecting travellers to language students. What a wonderful project! Imagine that you're going to Stockholm and all you have to do is browse for someone available in that time period to hang out with you a few hours a day and help you around the city.
More genius ideas...