I plan to identify a classroom activity that would support a low-cal application of a wiki. I'd like us to get our feet wet with the tool without getting to tangled up in deep mathematics.
We do have a project coming up that involves the students working in small groups to produce a final product but I do not yet see if it will be a good fit. I will have to give it some more thought.
Another thought is to create a wiki for AP Calculus that can be a study guide for the AP exam. As we pass through the year the students can update the wiki with key concepts, solution processes, etc. All students will have access. All students can contribute. All students can benefit. This might work!