Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Plan - Plan is a better way to organize.
Purp - A smart to-do list and goal tracker app
Drag for Gmail - Transform Gmail into organized To Do lists (like Trello)
Edison Calendar - Edison is a calendar app that helps you break big goals into multiple smaller milestones such that you have action items every day.
Tasks - The new task app from the team that brought us Wunderlist, Microsoft To-Do is a great way to manage tasks. List everything you need to do—or import tasks from Outlook, Todoist, and Wunderlist so you don't have to start over.