Class notes - Each week assign one student to write up the class notes, including important points and class discussion. Be sure to comment on the notes, and add additional insight from the lesson.
Wiki-pairs - Ask your students to partner with another student in class. These partners should comment on each others work, brainstorm new ideas, and generally help each other out. Private wiki pages make it easy to create private pages that only two students can edit.
Wiki group work - Create a page that only members of a group can access and monitor their progress on a research task over time. You can give feedback immediately and see who is pulling their weight!