Talkus - Chat with your website users from Slack
UI Movement - The best UI design inspiration, daily
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.
UI Garage - Specific mobile and web design patterns for your inspiration
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
UpLabs - The best material design, iOS & web resources, every day