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.
Hiver - Manage Customer Support, Sales and Projects right from your Gmail inbox. Collaborate with Shared Labels, Shared Contacts, email notes, email reminders and email templates
slalert! - Get notified in Slack when your company/keyword is mentioned
Clean Email - Clean Email is an online service that empowers you to take control of your mailbox.
Talkus - Chat with your website users from Slack
MailClark - The Slack bot for external communications