Talkus - Chat with your website users from Slack
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
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.
Carrd - Simple, responsive one-page site creator.
mmm.page - Dead simple, drag & drop personal websites
Smallchat Beta - Slack integration for chatting with visitors to your website