Boomerang Respondable - Write perfect emails with Artificial Intelligence
Just Not Sorry - Highlight 'weak' words so you can edit them out
Mailbutler - Mailbutler adds lacking functionality to email clients and increases your productivity
Boomerang for Gmail - Boomerang for Gmail is a Firefox / Chrome plugin that lets you take control of when you send and receive email messages.
TheRightMargin - TheRightMargin is a smart writing tool.
SlackScreen - Full screen public Slack channel display