I have a massive to-do list that is 8,917 lines long. It includes everything I need to do, remember, or think about. But it isn't unmanageable at all -- it is a .org file with code folding. The visible lines take up only two screens on my monitor.
Every project or business idea is in (parens) like Lisp. This keep my projects visibly separate from daily to-dos. I color-code the ()'ed projects by type by adding each one to my .emacs file like this:
(font-lock-add-keywords nil '(("(publish)" 0 font-lock-warning-face t)))
This lets me choose a color for each project. (I have yet to figure out how to assign custom faces. Still working on that.) My to-do list is a blaze of blue, green, pink, and red for the urgent items.
I format the top row of tasks like this:
* _1_ this is a task
* _2_ another task
* ___ yet another
* ___ lorem ipsum is boring to read
* ___ another task
* ......................
* (project)
* (business-alpha)
* (business-beta)
* (publish)
* (startups)
* (reading-list)
* (HN-reading-list)
* ......................
* ___ periods make a good visual divider for the list
* ___ another task
Projects are in (parens) and individual tasks have a ___ in front. Optionally I can rank the tasks with a 1, 2, 3 or 4 following the I-II-III-IV ranking model of Stephen Covey.
I highly recommend org-mode. I feel organized and on top of things even with so many things going on.
Edit: Edited to correct newlines.