Sonia Simone created a Squidoo lens called Use 37signals Backpack to manage GTD (Getting Things Done). It talks about how to use Backpack to create "a seamless, easy-to-use GTD implementation that will follow you anywhere you have an Internet connection."
Backpack is a deceptively simple set of tools that can be combined to produce a true blackbelt GTD implementation for hardly any money and in hardly any time...Far more flexible than the Davidco Outlook add-on, hipper than a hipster PDA, accessible from anywhere you've got a Web connection, cheap, insanely easy to learn, and faster than a speeding bullet. Backpack is the way to do GTD.
If you're trying to get organized and your system is giving you more pain than productivity, give Backpack a shot.
Here's the section on NAs ("next actions"):
"NAs" are "next actions," and they're organized by what David Allen calls context A context is just a situation you find yourself in where you can get something useful done. "Running errands" is a context. So is "working at my home computer."Some projects are also a GTD context. For example, when I'm in the mood to work on my Squidoo lenses, I want all of my next actions right on the Squidoo project page.
Other contexts are independent of any particular project. "Errands" are a free-floating context, as are "at my computer" and "phone calls." I find that it's easiest to group these together in logical order. I keep an "in the office" next action list on the same page as a "phone calls" list.
Backpack has a simple list functionality that lets you either delete a completed item or simply mark it checked, which moves it to a grayed "completed" area. Keeping the completed NAs around for a few days makes the act of completing them a little more satisfying.
Lists can be dragged from page to page, so if you find that a list doesn't work in a particular context, just drag it somewhere new. You can also drag NAs from one list to another.
There are a lot more specific tips at the lens page.
