I can show and sort these tasks either as subtasks or individually (if that makes sense).
- one-click access from system tray.
- I can set due dates, start date (it also allows for some basic time trackign, but I don't use that).
- I can set priority and risk for any given task.
- full search
- unlimited task lists, so I usually have a task list for every project I'm working on, whether it's a website, a book, or tasks around the house.
- I can have "tasks" and "notes" so the view is really compact, but if I have a task and, while working on something else, come across a key piece of information, and idea or whatever, I open the todo list and add my thoughts to the notes, so I don't lose track of it, but I don't get sucked into working on the task.