Workflowy - A better way to organize your mind.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
A5 - Takes notes in your browser. Elegant & simple.
Microsoft To-Do - Task management tool
Notepin - Extremely simple note-taking + blogging ✍️
Remember The Milk - Remember The Milk is a task and time management application for mobile devices.