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.
Doit.im - Doit.
Todo.txt - Track your tasks and projects in a plain text file, todo.txt. A todo.
TaskUnifier - TaskUnifier - Task Management Application
GTDNext - About Us.
The Hit List - Your life is complicated, but managing it doesnt need to be.