According to their website:
"Livemocha is the world’s largest online language learning community, offering free and paid online language courses in 35 languages to more than 6 million members from over 200 countries around the world."
I can't speak about their paid courses, but the free courses are pretty cool (at least for intro to language). I tried it for the first time last night for some portuguese practice. When you sign up you indicate the language you want to learn and your native language. They offer a wide range of languages -- Portuguese, Turkish, Mandarin Chinese, Arabic, Hindi, Spanish, Russian, etc.
In the lessons you learn (pictures, text, spoken), review (matching and multiple choice based on picture, text and spoken clues), write (from a prompt based on what you just learned) and speak (reading aloud and recording a text). The "review" section is corrected automatically. The written and spoken sections are submitted to "language partners" to review and give feedback. These language partners are native speakers who are also learning another language through livemocha. Once I completed my lesson in Portuguese, I was asked to review someone else's work in English.
Interested in learning a language? Check it out!