Purp - A smart to-do list and goal tracker app
Taskful - Deadlines, meet your match.
Nirow - Habit tracking: Automated, Siri-ed, Calendar-ed, and More!
Calendarist - Time blocking companion for Google Calendar
Things - Things is an easy to use task manager.
Centered - Centered helps you get into a Flow State faster and stay there longer so you can do your best work.