I have struggled with this as well, and being a Mac user I have not been able to take advantage of the Bonsai Desktop program. At first, I just used the To Do list and Palm desktop: I listed each project in To Do (category Projects) and assigned code numbers for each project at the beginning of the title: such as tea 05 (for project number 5 in the area of teaching responsibilities. Then each next action for this project added a hyphen: "tea 01-1 grade tests" On the Mac version of Palm Desktop you can sort to-dos alphabetically, so I could easily see which projects had next actions and which did not. The only problem with this for me was that I could never remember which project it was from the number, so I would keep looking it up in the Projects list.
Then I discovered Life Balance, which has a beautiful desktop program for the Mac (and one for Windows as well), and it syncs very well with the Palm. On the Desktop, your outline shows all your projects and their next actions, and when you are in the To Do List view, if you just select a to-do and go to the Outline, it automatically takes you to the same to-do, so you can easily see what the project is. (On the Palm it's a little tricker; you select the to-do, choose Move, and then look at the info there, then push Cancel so that you don't actually move it).
If you try out the setup for LB and GTD from Ratz (go to the Llamagraphics.com discussion board), you will find more help; the best idea is that you assign every project to a place called Projects (that is always closed). When you go to this place in To Do View, it gives you a list of every project that does not have next action assigned; so you can see at a glance, any time you want, which projects do not have next actions assigned.
If you want to just use the Palm's built-in apps, the best idea I have seen is by Randall on the GTD_Palm yahoo group (messages 13443 and 13574), where he makes a project a to do and just changes the front part of the title each time he changes the next action; the to-do only gets checked off when the project is completed. You keep a record of everything in the attached note. This is called the "pigpog" method. Randall in message 13574 switched to using the MemoPad instead of the To Do app (which I prefer: due dates and priorities), so don't be confused by the two different versions.
To summarize: while I think Life Balance is perfect for what you are asking for (especially with the Desktop program for Mac and Windows and its outliner/to-do automatic linking), you can use any outliner as long as you keep a note in the to-do of what the project is, such as: grade tests {finished preparing for Latin class} or grade tests re:finished preparing for Latin class. Then you will be able to connect them during the week and at the weekly review.
George