SendLater - Email scheduler for Mac Mail.
Trello for Slack - Organize anything with anyone, inside Slack
Assistant.to - GoToMeeting. Put your GoToMeeting link in the Assistant. to "Location" field. Once the recipient selects a time, you will both receive an invite with a unique GoToMeeting link.
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Shortwave - Email smarter & faster with a reinvented experience for your Gmail
Halp - Slack-first ticketing for internal helpdesk