I wrote about phpGedView before. I have been using it as the hosting software for our genealogy web site. I had only been using it as a read-only view of the data, and using a desktop application to modify the data.
I just realized that there is pretty cool feature. My sister wanted to update some information, so I created an account for her, and she was able to do her own edits. You can also configure accounts so that an administrator has to approve of changes before they will be posted.
This is turning out to be pretty good software for family collaboration.