First, there was Wikipedia. Now, there's Wikibooks, an open-content collection of textbooks on all subjects. In keeping with the spirit of Wikipedia, anyone can edit one of the textbooks. I looked specifically at the textbooks for "how to write a research paper in history" and "history of computing," and while they are pretty short and bare-bones at this point, I think the idea has potential.
Also, I'd be interested in hearing your thoughts about the idea of having students write Wikipedia entries for course assignments, rather than (or along with) term papers. I know that at least one professor has implemented this idea. Would it tend to result in better output from some students, since they know that their work could be read by people "out there?" Should the results be placed indiscriminately on Wikipedia, no matter the quality of the submissions? As a student, would you prefer to write a term paper to be viewed only by your professor or TA, or to write a Wikipedia entry that could be viewed by any number of people? I'd love to see opinions from both teachers and students on this question.