I've tried using both goals and folders for projects in the past and while I appreciate the idea that finishing a project means that I've met a goal, I've stuck with folders for a philosophical reason: I use folders to manage commitments. Many of my commitments (naturally) are projects. So, my project folders are labeled with a prepending "PRJ:". My "one-off" next actions, which are essentially commitments themselves that need no "stake in the ground" as David Allen would put it, are in a folder called "Simple Tasks" that I generally ignore in Review, because they are short-lived and handled daily in context lists anyway. If this sounds weird, just remember that the basis for GTD is to manage your commitments and place reminders to perform next actions in a place where you are sure to see them when you need to -- the idea is NOT to make the next actions themselves the focus, because this is why simple to-do lists fail.