Google Calendar - Spend less time managing your day & more time enjoying it
Outplanr - Turn your to-do list into a real work plan
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.
Ink Calendar - Plan your day with your pen
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Basecamp - A simple and elegant project management system.