Duolingo is a fantastic new way to learn a new language for free while also helping to translate the world wide web. The interactive lessons teach you the fundamentals of the language and motivate you with points and community features. Currently Spanish, German, French (in beta) and English (for Spanish speakers) are offered.
The program started as a Carnegie Mellon project years ago to transform language translation into language education (one of the top skills most of us wish we had the time to invest in). Duolingo not only helps people learn a new language, it also tackles translating the whole internet: members learn while translating websites and other online documents. Advanced/fluent users get complex sentences and tasks to translate, and rate each other's work, while novices get more basic words and sentences to translate ("where is the library?").
Once you sign up, you're walked through some basic lessons and presented with a skill tree with more lessons. Earn points and see your daily progress, as well as get a daily email reminder to stay on track. You can connect to Facebook to share your progress with others, post something in your chosen language for your followers, ask questions in the community and so on.
Portuguese, Italian and Chinese lessons are coming later.
Duolingo just opened to the public today, so head over if you want to do your part in translating the web and learning a new language at the same time.