Hi there, @bobosox.
Personally, LinkedIn my main channel of communication with attendees and guests from a content marketing meetup I host here in Brazil. Like @Jordi, I'm also using WhatsApp for mobile messaging with attendees and supporters, and Skype for aligning co-marketings and gathering feedback from customers.
Interestingly, my company is developing a marketing automation & engagement platform with a built-in proactive live-chat feature. Recently, when we reunited with beta-testers and customers to gather feedback about the software, almost all of them told us that the website live-chat feature turned out to be their most valuable engagement channel with leads and customers, which previously was made only by email.
I really liked VentureApp's proposal, the really clean web UI is perfect to focus on a productive messaging, but personally I've had some trouble in the user onboarding when typing my company's website. Beside that, congratulations for the product!