Google Calendar - Spend less time managing your day & more time enjoying it
Tweek.so - A concise and simple weekly to do list calendar app to organize your tasks online. A lightweight weekly planner to maintain your focus and boost productivity week over week.
Mixmax Calendar - The fastest way to schedule meetings with anyone, anywhere
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Sunsama - Calendar and scheduling for teams
Teuxdeux - TeuxDeux / What deux yeux have teux deux teuxday?