Are you familiar with google docs? It's an amazing tool that makes collaboration a snap! Google users (and non-google users) can create a document and then share it with others giving all invited members the authority to add, delete, and edit the document with all changes being able to be tracked. This document lives in cyber space and not on any one person's hard drive. How could this be helpful? Remember being in school and the pain of having to find a time all of your group members could get together to work on a particular project? Well, with google docs that is no longer a problem. Simply invite all members of the group into a google doc project and they can edit and tweak the paper to their hearts content.
Writeboard is similar to googledocs in that many users can create and edit a document together. The big diference is that unlike googledocs that constantly saves and changes your original document, writeboard continues to make new pages so that users can see the changes made to the original document and go back to earlier version if necessary. Students do not need a google account in order to use this which is another advantage. Only those invited by the creator can view the document.
Some helpful links and other fun resources on online word processors: