("Getting Things Done") methodology of this one David Allen chap.
http://www.davidco.com/ (Note: Not the wide tie-wearing Dave Allen who had a BBC comedy show in the 60s)
It's a bit more fully-featured to-do listmaker. You can group things by "projects" (goals with subtasks), then add actions (little things you have to do to achieve the goal), and to each action assign a "context" (I think of it as "where.") You can assign due dates and estimated times. You can switch views between projects and contexts.
An enthusiastic user has written an Apple Script to clone projects. This is useful for me because any bug fix at work follows a fixed series of steps. Cloning a project for each ticket I have to keep track of (whether mine or those of the two yo-yos I supervise) enables me to check off tasks as they are done.
Omni Group's software is the bomb, generally. I've used OmniGraffle and OmniOutliner before.
http://www.omnigroup.com