Commandline Challenge - Test your command line skills
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Prompt - Prompt provides fully-integrated writing education solutions, combining instruction, curriculum, and feedback. We support educational institutions, companies, and individuals.
Any.DO - The #1 task management app used by over 11 million people globally, Any.do is your free mobile and online task manager for Android, iPhone, Web and more.
Cwiki - A Command line interface for searching Wikipedia!
Microsoft To-Do - Task management tool