I find this article (based on a video that is also there) very interesting. The author goes through a list of online resources that people can use to find ways to learn languages online. It even offers a link to CALICO (Computer Assisted Language Learning Instruction Consortium) reviewed course.
This article, which is easily found on Google, is nice for someone like me who is new to Twitter and has not thought of ways to use in class. It also give nice links to the ideas provided to better explain how to use the suggestion.