Talkus - Chat with your website users from Slack
Slackin - Create your own public Slack chat community
Chatlio - When you have a business to run, your average instant messaging software just will not do. You need an internal presence upon which your entire team can collaborate on. Read more about Chatlio.
Message Bender - Backup and delete all Slack messages in bulk
Slacking Pigeons - Chat in real time with your users directly from Slack
Hamster Pad - A social network built on top of Slack