Google Docs

I used Google Docs when I was in school a fair bit - particularly when I was completing my fourth year project with three other classmates. That report was massive and had to be worked on by all team members at all times. Google Docs enabled us to all have the report open at the same time and be editing together. At the bottom of the shared report, it would state all the other users who had that document open. You would then be able to write away in whatever area you desired. Upon saving the document it would be updated with all the other users information. If there was a conflict between user (ie. two people had made changes in the same location) you would be given the option of which changes to accept. It works in a similar fashion to the shared documents within the new version of Microsoft Office, which is also a handy feature I have become accustomed to at work.