Trello for Slack - Organize anything with anyone, inside Slack
SendRecurring - SendRecurring allows you to setup, send, and maintain scheduled email reminders.
Actions from Slack - Turn Slack messages into tickets, issues, tasks, and more.
Recurrr - Send recurring emails
Slack Jira Integration - Easily keep issues moving right from Slack
Followup.cc - FollowUp for email is a lightweight productivity suite that keeps your conversations and tasks from slipping through the cracks. Set perfectly timed reminders that arrive at the top of your inbox, right when you need them.