Stixy allows you to create tasks, appointments, files, photos, notes, and bookmarks on their Stixyboards, organized in whatever way makes sense to them. Then they can share Stixyboards with friends, family, and colleagues.
Like WallWisher you could set up a Stixy board for class projects, for brainstorming or for the collection notes and resources.
You can control who has access, and whether visitors can read or amend the board.
Here’s a demo board I’ve set up: http://www.stixy.com/guest/86940
It’s well worth a look: http://www.stixy.com