One of my courses (second year Humanities/Culture course) explores how the Arts have been realized in 3D multi-user environments - namely, Second Life. This year I'm piloting an assignment that seems to be a winner.
I have the class divided into group of 3-4 students (total 30 students). Each group is responsible for conducting an 'in-world' curatorial tour focused on 4-6 exhibits/pieces in at least 2 different locations. The groups are graded on the conceptual design of their tour, the relativity of the exhibits chosen to the main idea of the tour, their ability to appropriately and correctly use key course concepts and theories, and their 'choreography' - that is the fluidity with which they facilitate the movement of class avatars from place to place.
The groups each post an itinerary and statement encapsulating the main ideas of the tour and their relationship to the pieces they selected. Every 'observer' is marked in terms of their active engagement during the tour as well as on a half page response to the tour which is posted on the course Moodle. Before the first group's tour, I conducted one myself to model what I was seeking and to give them an opportunity toget used to navigating in world - a first for many.
The in-world conversation - conducted via IM and avatars, was way more engaged and evenly distributed amongst the students than in the classroom.
This can be used in other environmens too -internet, geocaching, even RL! :-)