I know that GTD is usually implimented with some sort of list of Projects (like @Projects) and I've done that for years. However, the problem with that approach has also been discussed here--it is difficult to track your next actions by project if there is no way to somehow group them together.
One approach--consider Projects a Contact in Outlook and use the contact organizational system of Outlook to organize projects. Another approach--use an outline-style system to track Tasks (Shadowplan, etc..
What I've taken to doing recently is to make ad hoc categories in Outlook for each project, and then list the Next Actions under them, being sure during my weekly review that at least one of those Next Actions is on one of my @Context lists.
The result is that my Tasks View in Outlook has all my Context Lists at the top (@Calls, @Desk, etc.) and then a whole series of longer descriptions at the bottom, each one a category describing a Project holding a list of items that are not yet really Next Actions and therefore do not yet go on a Context List.
This seems to work pretty well. Is anyone else doing this or has anyone found a better way?