Duolingo

Duolingo is a free language-learning website and crowdsourced text translation platform. The service is designed so that as users progress through the lessons they simultaneously help to translate websites and other documents. Currently, the site offers only Spanish and German courses for English speakers, though it has plans to expand to French, Italian and Chinese in the future. Duolingo launched in private beta on November 30, 2011, and has accumulated a waiting list of more than 100,000 users. As of December 22, 2011, the service has translated over 24,000 sentences.