I work on a complex application where different teams work on their own modules with a degree of overlap. A while back we got a Mediawiki instance set up, partly at my prompting. I have a hard job getting people to actually use it, let alone contribute.
I can see a lot of benefit in sharing information. It may at least reduce the times we reinvent the wheel.
The wiki is not very structured, but I'm not sure that is a problem as long as you can search for what you need.
Any hints?