Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
C-Organizer - C-Organizer is a robust software tool designed for the professional manager that permits them to organize business activities altogether.
Todo.txt - Track your tasks and projects in a plain text file, todo.txt. A todo.
Info Select - Info Select is a Personal Information Manager that organizes Internet data, notes, to-do's...
EssentialPIM - EssentialPIM is a free Personal Information Manager that keeps up with the times and lets you manage appointments, tasks, notes, contacts, password entries and email messages across multiple devices and cloud applications.
AllMyNotes Organizer - AllMyNotes Organizer is a multi-functional hierarchical information manager for Windows.