Wikis are a great tool for student projects. Teachers often think of them when they want students to do something collaborative, but, wikis are also a great tool for individual work; particularly for research papers.
Working in a wiki makes it easy for students gather background research. The commenting features are a great way for peers and teachers to provide constructive feedback and suggest additional resources in real-time, as the paper is evolving, instead of waiting until the end of an assignment to offer feedback. Most wikis have automatic revisioning features, too, which save before and after versions each time a change is made to the wiki.