In some situations in which you are writing a document with other authors, it becomes important to know who wrote a passage before you change it. Policy documents in particular, or those whose authors have a stake in the positions expressed, are those in which revealing the authorship is important to successful collaboration.
AuthorViz works on Google Docs revision history, and is available in the Chrome store.
Try it at AuthorViz
Current Team member:
Previously on this Project: