Marker.io for Slack - Turn screenshots into Slack messages ✌️
Sortd - Rated the #1 App for Gmail
Instashot - Access text from any image instantly.
KanbanMail - A Kanban board for your emails.
ScreenTray - A better way to capture, annotate and share screenshots
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.