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.
TaskPaper - Plain text to-do lists for Mac
Drag for Gmail - Transform Gmail into organized To Do lists (like Trello)
TickTick - TickTickis a cross-platform to-do list app & task manager helps you to get all things done and make life well organized.
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.