Reminder - A better way to keep track of your reminders 📝
Sortd - Rated the #1 App for Gmail
Wonder for Slack - Remember the things your team forgets
KanbanMail - A Kanban board for your emails.
Nusii - Collect content & files from busy clients
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.