We have adopted Slack recently with a small 12 person (and everyone knows everyone) team and it works great. It really brings down distraction of people coming over to ask questions, they can just ask the question of a group and get it resolved by someone. We have Lync as a company wide (1000s) community messenger but for small teams this works great for collaboration of small groups. I am actually shocked that Microsoft doesn't have a solution like Slack built into Lync (Skype for Business now.) I mean it's possible they could buy Slack...but anyhow Slack is made for smaller teams. If you want a community use IRC (non-corporate), Skype or Google (corporate), etc.