Google Calendar - Spend less time managing your day & more time enjoying it

Microsoft To-Do - Task management tool

Jorte - Schedule books must be practical and has a good design.

Todoist - Todoist is a to-do list that helps you get organized, at work and in life.

Business Calendar - Powerful and easy to use calendar app for Android including weather, widgets and tasks.

doo - A smart, simple app for reminders and to-dos