The following provides a nice article of how people are learning language on the web.

NYTimes Article

From a learning standpoint, here are some research-based reasons that these interfaces might be good in helping people learn a language:

  1. Most of the learners are motivated to learn a language.
  2. Learners have to engage in retrieval practice, which research shows is a strong support for remembering, and also to test understanding.
  3. Learners get feedback on their retrieval-practice efforts.
  4. Learners are probably spacing repetitions over time.
  5. Learners in their practice are engaged in situations that are contextually similar to the way they might utilize a language–by actually engaging in a conversation.
  6. Because they provide a way for learners to overcome the fear of initially speaking to others in a foreign language, learners may be more willing to practice for real, which of course will aid their learning.