Talkus - Chat with your website users from Slack
Hamster Pad - A social network built on top of Slack
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.
sup3rS3cretMes5age - A safe, simple tool for one-time (self-destructing) messages
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Tsu - Social that pays