A couple of weeks ago I got frustrated hunting for the phone calls to make on my @Office list on the Palm Desktop. Since I can only make my work related calls from work, I put them on that list instead of an @Calls lists or creating an @Calls - Office list.
I tried something new: when I created a next action that was a phone call, I assigned it a priority of 2 (the default is 1). Since I wasn't using priority codes before this, all of my phone calls would be grouped together at the bottom of the list. This gave me the double benefit of being able to see all of my @Office actions (unlike an @Calls-Office list) while also having a distinct area for calls, which tend to be higher in priority than other actions. All of a sudden the action list became much clearer.
Then I started applying the concept to other contexts. I left offline @Computer NAs at their default 1, but assigned a priority of 2 to NAs that required being online. The big surprise was recognizing how many actions got ignored because I unconsciously assumed I needed to be online to be productive. Months before, when I had separate @Computer and @Computer-Online lists, I would ignore the offline list.
Another context where the technique is helpful is the @Anywhere list. I realized that I really had two "Anywheres": actions that I could literally do anywhere with only what I carried on my person at all times (e.g. Treo and jotter wallet), and those that required a walk to the car to get what I needed (writing and reading).
I assigned a priority of 2 for personal Waiting Fors, and left work related WFs at 1.
Someday/Maybe, which I've reorganized a couple of times, has become a little more intricate: (1) things to buy, (2) books and documents to read, (3) things to learn, (4) general projects.
I'm still experimenting with the system. For instance, I might take all of my calls and put them on a single @Calls list with 1, 2 and 3 codes for work, home, anywhere respectively.
If you want to try this out, I recommend leaving the subgroup with the greatest number of NAs at the default 1 setting, which will save you the extra step of having to assign a number to each of them. To assign the rest, you can use the speed key sequence: Alt-r | right arrow to number | spacebar to select | Enter to OK.
To make this work on the handheld, make sure you have your Tasks prefs set to show priorities. If you add a new action onto a list, you'll need to have a task highlighted that matches the code you want to assign to the new action, otherwise it will assign the number but won't regroup it with the appropriate number.