At my previous employer, we used a Mediawiki instance for approximately everything in projects: documentation, design sketches, work packages, internal tool FAQs and Howtos, project meeting minutes. Bug tracking, however, happened in Bugzilla. We had a sophisticated naming convention for different types of pages.

In retrospect, I wouldn't track work packages and progress in a Wiki any more (instead use something that can actually add up the "time spent" column...), but the rest was fun to work with.