We're using a wiki. I recommend MoinMoin because
- very simple to setup (even on a Laptop)
- very simple to backup (you can even commit the wiki to a version control system to sync it between, say, laptops for offline usage).
- nice syntax
- easy to extend
- Easy to search
We're not using something like Word because:
- Documentation rots too fast
- Searching all documents is a pain
- Linking between information bits is a pain
- No diff between versions
- Binary format which craps the hell out of any VCS
- No deep bookmarks
- Documents grow too big and then they become clumsy: Split (and no searching anymore) or wait ages to load.
