Slack - A messaging app for teams who see through the Earth!
Sortd - Rated the #1 App for Gmail
Teamwork - The Project Management App for Professionals. The most powerful and simple way to collaborate with your team.
KanbanMail - A Kanban board for your emails.
Sametab - Share company announcements in your coworker's new tab
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.