It seems like you need duct tape for all of the little things, so I think anyone who mentioned the wiki before made a great observation. I would suggest
Twiki or MoinMoin.
They are mature.
They are free.
They are platform independent and low deployment.
They have access control and authentication.
They have versioning.
You can subscribe to email notifications or RSS feeds of changes to pages.
They grow in an organic manner rather than having too much structure.
They split the cost of management.
They can interlink information.
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It seems like you need duct tape for all of the little things, so I think anyone who mentioned the wiki before made a great observation. I would suggest Twiki or MoinMoin. They are mature. They are free. They are platform independent and low deployment. They have access control and authentication. They have versioning. You can subscribe to email notifications or RSS feeds of changes to pages. They grow in an organic manner rather than having too much structure. They split the cost of management. They can interlink information.