Business Calendar - Powerful and easy to use calendar app for Android including weather, widgets and tasks.
TimeTune - TimeTune improves your daily routine and allows you do more things with your time.
FCorp My Calendar - Manage diary/note, schedule, todo, birthday, etc.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
AnCal - AnCal stores yours appointments, tasks and notes, which you can easily add and edit.
Google Calendar - Spend less time managing your day & more time enjoying it