Divide students into groups and have each team research a different component of a project or subject. Now reorganize everyone into new groups that include one member from each original team. Students in these new groups share what their team learned, allowing everyone in the class to hear about the entire subject.
This ensures that all students have the opportunity to present their findings, rather than hiding behind their peers – people learn more when they have to explain the information to others. It would also be helpful to have them post their findings to a class wiki so everyone has access to the material at any time.