"Wikis always start off with the best of intentions. Sharing knowledge in a centralized place that everyone can edit. Wikis are useful but they can be difficult beasts to wrangle. Out of date information, broken links, bad formatting left unfixed, etc. The list is endless.
Keeping them in working order requires vigilance. It can all start with one crappy page. I liken it to the Broken Windows theory.
"Consider a building with a few broken windows. If the windows are not repaired, the tendency is for vandals to break a few more windows. Eventually, they may even break into the building, and if it's unoccupied, perhaps become squatters or light fires inside. Or consider a pavement. Some litter accumulates. Soon, more litter accumulates. Eventually, people even start leaving bags of refuse from take-out restaurants there or even break into cars."
This might as well have been written about wikis.
Pick one page, one section, or one space in your local wiki and make it yours. If you can keep that area from looking like a broken window, perhaps you can get people to continue to care about it and help maintain it. In turn this should help communication throughout your entire community. That's my motivation behind fixing these broken windows.