I've been doing some research lately into how an "achievement system," popularized by modern videogames such as Halo and Gears of War, might be a great way to spur student participation in wiki projects. I just finished reading a great essay called "Using Wiki technology to support student engagement: Lessons from the trenches" published in Computers & Education 52.1 (2009). The author, Melissa Cole, found that most of her students weren't interested in her wiki at all, and no one had made any contributions to it after 5 weeks! The reasons ranged from the classic "I just couldn't figure it out..." Uh, come on, it's a wiki--you know, the simplest possible website to edit? The students were seniors, so I just don't buy that. The others claimed it was too time consuming, or, more honestly, that they just didn't have an interest it. As far as I can tell, the wiki wasn't part of the grade, so that probably explains a lot of Cole's trouble.