I started my GTD setup with Proximo's setup but then I simplified them:
First a bit of background:
I use Outlook 2007 at work with Exchange Calendar that is synced to my Nokia
I use Gmail and Google Calendar as personal systems
Toodledo manages all my tasks and I use subtasks
I use the Status setting:
Next Action - it speaks for itself
Active - for actions that I got to do but are not next actions (meaning not enough priority in my life or part of follow ups of projects)
Planing - the parent task of small projects (as Proximo I have the +Big Project and them the -Project: Insert task here)
Delegated - when I can, of course
Waiting - When I need answers to move forward
Hold - Things my boss told me to wait
Someday - My someday list
Canceled - For things that were canceled completely but I still wasted time in them (this is different from Hold)
I use Folders for big projects, things that are really very complex but have the common theme --- like Folder: house remodeling, +Remodel kitchen, -kitchen: Pick counter top
Meeting with X
Meeting with W
I use the start date in my tasks with the default for the day they were created, this allows me to see in my review if an active task is getting old and must go to next action or simply be deleted from the system. Is very useful mostly for the waiting items.
I use the goals system in Toodledo, although they aren't a column in my tasks, for keeping track of my altitude in GTD (i know they are only 3 and in the GTD book they are 6).
I review my system twice a week (biweekly review) and my Inbox are Notes on my cellphone (Sticky Notes for Symbian) that always goes with me everywhere (so a super Inbox processed once a day at least) or a BCC of emails to Toodledo (that have no context so easy to see).
I always start my session in the Status, Next Action View, Ordered by Context
Hope this system helps anybody out there. Any questions fell free to ask.