My tickler files live in a hanging file drawer in my desk. (I am going to be dropping things in them throughout the day, so it has to be handy.) Incidentally, just above that hanging file drawer is a drawer that serves as my inbox and pending items. Pending items are in one small stack (the requirement on those is that there has to be a corresponding item on the task list). The other small stack is for items where the physical item is the reminder that action needs to happen.

As for the A-Z files, those are in two filing cabinets. If I understand David's intentions correctly, these are simply your reference files. The A-Z part is that instead of having different drawers devoted to different subjects, each one starting with its folders inside, you just have one continuous system rather than subcategories.