Habitica - Habitica is a free habit building and productivity application.
Google Calendar - Spend less time managing your day & more time enjoying it
Loop Habit Tracker - Loop Habit Tracker (AKA uhabits) helps to create and maintain good habits in order to achieve their...
Business Calendar - Powerful and easy to use calendar app for Android including weather, widgets and tasks.
Flow Dashboard - Habit, task & goal tracking + quantified self
Jorte - Schedule books must be practical and has a good design.