Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Trello for Slack - Organize anything with anyone, inside 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.
LiveChat - LiveChat - premium live chat software. Approach customers directly on the website, make connections and drive more sales using LiveChat.
Halp - Slack-first ticketing for internal helpdesk
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.