I do, sort of. I'm just getting off the ground, but I have these cards: Inbox/Unsorted, Next Actions, Waiting On, Ideas, Reference, and Done.

I haven't yet, but I think a lot of people use labels extensively to further organize (e.g. is this to do at #home, #work, an #errand...? will this action take #5mins, #30mins, etc).

I like Zendone. It connects Google Calender and Evernote. But it is still in private beta.

Thanks, just signed up— although I'm wary of moving my GTD life off of Trello. Still, open to it... and I have to say, the Zendone website is beautiful.