A tip from Sophie:
There's a product called the UNCALENDAR--it's not really a regular notebook but some people would like it. The different sizes are $19 and $15 (I think, that's close enough). What's cool is that as a calendar it's totally blank. You put in all your own dates even, and it's more or less a monster notekeeping, to-do system, for everything, except your writing. I used to have one of these and was very happy with it, it seems to have gone through some changes during that time. The point is if you find yourself organizing things in your Moleskine when you woud rather not, this might be a good calendar/organizing place for you. There's something about having everything BLANK in these calendars, your own creative space, that I think would appeal to a lot of notebookers, me included. I suspect this would go over very well with the "Getting things done" types as well.
Check out their website.