Is there a LAN equivalent of Google Docs?

Google Docs' feature of allowing live editing from multiple collaborators is a very useful tool indeed. But, I wouldn't trust my internet connection with an important project. It would be nice if collaborators could edit the file over a local network.|||As far as I know, there isn't one; however, the only plausible suggestion I have is file sharing over a shared network, but that's probably a very inefficient alternative.