ToDoList is completely free and is available here (link removed). ToDoList is licensed under a Creative Commons Attribution-ShareAlike 2.5 License.
ToDoList is a rare form of task management tool, one that allows you to repeatedly sub-divide your tasks into more manageable pieces whilst still presenting a clean and intuitive user experience.
ToDoList has been in continuous development for the last 5 years and is an ongoing project.
Tasklists are stored in XML which provides many opportunities for advanced formatting and printing using stylesheets.
ToDoList's flexible design makes it ideal for both IT related projects as well as more general GTD uses.