Any decent task-list apps out there? #Life

Outlook has a task list, but it's pitiful. I've looked around for freeware or shareware task-list apps, and the ones I've found are no better. They all have two fatal flaws that make them completely unusable in real life:

1. They all give you a flat list. Pathetic. In real life, tasks have subtasks, which have sub-subtasks, etc. (Especially when you have attention-deficit disorder, and need to write down all the details if you hope to remember them long enough to actually do them.)
2. They all give you a measly three priorities: high, low, and neither. Within a priority, everything is alphabetical. Yuck. In real life, you need to be able to reorder things arbitrarily, and three priorities won't even come close.

Has anyone used any task-list programs that actually support hierarchies and arbitrary ordering? I'm thinking of writing one, but that'd be silly if there's a usable one out there somewhere. (That won't necessarily stop me, mind you; but I might as well see what's out there before I write one of my own.)

One other feature that I would really like (but could probably live without, if there's an otherwise-decent app that doesn't have it) is the ability, at the start of the day, to say, "Here are the things I think I can get done today." Then, at the end of the day, I could see whether I did get them done, and if not, I could try to figure out why, or why not. (At this point it would be helpful to see which things did get checked off that weren't on my "Today" list.)

This "Today" feature might help on those days when I'm thinking to myself on the drive home, "Okay, now exactly what was it that I accomplished today?" And a history of all these "Today" lists would be extremely helpful when I'm trying to remember what I accomplished during the last review period.