My students principally work on translating articles from English Wikipedia to Spanish Wikipedia, with an emphasis on working with the communities of both languages.
This type of assignment takes advantage of Wikipedia as a focused social situation, something that foreign language learners, especially advanced ones, need. This kind of interaction mimics real world challenges such as using the language for communication of ideas and adapting the requirements of a previously-unknown social group. It is real enough to produce culture shock in a number of students. However, the same frustrations are also motivational as students know they are interacting with real people and their efforts have an effect outside the classroom.
(CC-BY-SA 3.0) by Alejandro Linares Garcia