I've been thinking about how to have more dynamic wikis for sharing knowledge in a company, something like a document on Google Drive encourages much more active participation. There are some projects going in this direction of having real-time wikis like Rizzoma and Kune (based on Apache Wave), but it seems group-chat solutions are growing features (long-term archiving, full-text search, tagging) to fill a similar need. I'm trying out Rocket.Chat next, it seems to be the most full-featured Open Source Slack clone available at the moment.