The largest wiki in the world is Wikipedia. As in all wikis, users can edit any page, discuss the contents and see the history of previous versions. People interested in particular pages can request automatic notification whenever those pages are changed, allowing for community self-checking. Wikis trade authority for inclusiveness, and are good sources for wide ranging research.
Many organizations use wikis to communicate between physical meetings and to save time discussing new ideas and changes to texts. Organizations with multiple generations of participants could benefit from using a wiki to store and evolve knowledge from one generation to the next. Communities of interest can also use wikis to develop a list of problems and shared ideas for solutions. See, for example, WikiPod, a wiki about iPods.
I can help your organization select, set up and learn to use wikis.