Another really good implementation is Quill (quill.chat). It has a "room type" option where a room is either threaded or free for all. In a threaded room it's a

Another really good implementation is Quill (quill.chat). It has a "room type" option where a room is either threaded or free for all. In a threaded room it's a little more message-board like, every top-level post has a topic and such, so it starts a thread. In a free-for-all room it's basically the same as Slack.