Nirow - Habit tracking: Automated, Siri-ed, Calendar-ed, and More!
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Gone - An ephemeral to-do list
Any.DO - The #1 task management app used by over 11 million people globally, Any.do is your free mobile and online task manager for Android, iPhone, Web and more.
Taskful - Deadlines, meet your match.
Microsoft To-Do - Task management tool