Todo List Software For Mac OS X

Task Coach is a simple open source todo manager to manage personal tasks and todo lists. Task Coach is designed to deal with composite tasks.

Features of Task Coach :

Creating, editing, and deleting tasks and subtasks.
Tasks have a subject, description, priority, start date, due date, a completion date and an optional reminder. Tasks can recur on a daily, weekly or monthly basis.
Tasks can be viewed as a list or as a tree.
Tasks can be sorted by all task attributes, e.g. subject, budget, budget left, due date, etc.
Several filters to e.g. hide completed tasks or view only tasks that are due today.
Tasks can be created by dragging an e-mail message from Outlook or Thunderbird onto a task viewer.
Attachments can be added to tasks, notes, and categories by dragging and dropping files, e-mail messages from Outlook or Thunderbird, or URL's onto a task, note or category.
Task status depends on its subtask and vice versa. E.g. if you mark the last uncompleted subtask as completed, the parent task is automatically marked as completed too.