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.

Meetingbird - Powerful meeting scheduling and notes — right in your calendar

Drag for Gmail - Transform Gmail into organized To Do lists (like Trello)

Tooqan - Find out how effective your meetings are

KanbanMail - A Kanban board for your emails.

Worklife - WorkLife is a web and mobile app that helps you run highly productive, engaging meetings.