PBwiki ... a way to collaborate on documents

No doubt you've heard of wikipedia ... this is a smaller-scale version of that where you can make your projects public or private.

I've just started using this to collaborate on a couple of projects. For one I am collaborating with a coauthor from another state, and we've set up a private wiki at pbwiki.com (the pb is in "as easy as peanut butter & jelly"). PBwiki is free for educators.

This way, our proposal can "live" on the wiki and we can both access it to make changes and the document lives in real time. In this manner, we avoid passing the document back and forth over email.

If you have online students writing a joint report or working on a project, this might be a nice way for them to collaborate with each other. If they let you into their "project wiki" then you could make comments on their work... similar to when you make comments in a draft document.