Here's another interesting organizational method using index cards. I don't find coding too useful myself, but maybe you do...
I prefer just creating a card for each concern or task. For example, a card might say "send in rebate form." At this point I haven't gone through the whole David Allen GTD process and figured out what my next action is, but I've recorded the thing I need to do and gotten it off my mind.
Later, when I have a moment and I'm reviewing my cards, I might decide that the next thing I have to do is figure out the address where I need to send the form. (Because Fry's in their infinite wisdom didn't provide that information. True story.)
As I work I jot down notes on the card about the current status of the issue so that the next time I look at it I remember what I need to do. If I left a message for someone, or I need to find a phone number, or someone's promised to send something to me, I note that. Et cetera, et cetera.
The card remains a work in process until the whole thing is done, then it gets filed away and taken out of the stack of things I need to worry about. If I decide that I don't need to do it now, I put it in a separate pile. Usually I focus on a pile of cards that I'm going to work on today.
I'm also experimenting with a tickler system. Sometimes I have a concern/card that must happen at some point in the future. If it's within the next 31 days, it goes behind the tab for the day when I estimate I'll do it. If it's months away, it goes behind the proper month's tab. If I'll do it tomorrow, it moves to the next day's tab.
Damn I love those index cards.