We had a quite notable recent classroom experiment in assigning students missing Wikipedia articles to write. Dig this first edit!
Writing a new article that will stick really isn’t hard: a few paragraphs, some references and some indication that there’s a reason to care will do the trick. (Go on, stretch yourself beyond web comics.) Anyone with an hour or two can produce something well worth keeping with Google Scholar. If you have access to a university library, it’s ridiculously easy.
Rather than just telling your students “go write something,” set them loose on a list of red links, requested articles, missing articles or the missing articles project. Discussion on WikiEN-L suggested Gaelic footballers, Indian and South African politicians (indeed, politicians from anywhere that isn’t the US or Europe), biographies from before the twentieth century (check any public domain biographical dictionary, particularly ones not in English), every scientist in a prominent national academy …
(Don’t forget to tell the school and university projects list.)