I'd be interested in getting peoples' take on the recent Freakonomics podcast, "Is Learning a Foreign Language Really Worth It?" http://freakonomics.com/2014/03/06/is-learning-a-foreign-language-really-worth-it-a-new-freakonomics-radio-podcast/
The Economist reviewed the podcast here,
1) The premium for knowing another language ends up being pretty significant over one's life (especially for languages which few people in your country know, but for which there is a big demand like German);
2) Foreign languages command more value in export-driven in economies; and
3) There are always opportunity costs when you study a subject - literature, art, history - and yet the authors don't analyze the ROI of these subjects.