When Doctor Who returned to television, the BBC started in 2006 having Advent calendars counting down to the Christmas episode of Doctor Who. The name was later changed to Adventure calendars and had a variety of wallpaper downloads, interviews, puzzles, sneak peeks, and other advance info appearing each day. The previous years can still be viewed. The countdown is slightly confused this year, as the season (2015 series) hasn't ended yet. So this year the beginning of the Adventure calendar has interviews and advance promo pictures of the season finale. It can be found at http://www.bbc.co.uk/programmes/articles/16TJvP8hHBBVWyfxlJw9BP8/doctor-who-adventure-calendar-2015.
Diane Duane has a new release in her Young Wizards series coming out in February, but she has a self-published book out now. Her Advent calendar has snippets of dialog not used in one of the seasonal short stories. It can be found at http://www.youngwizards.com/interim-errantry/2015/12/01/how-lovely-are-thy-branches-advent-calendar/.
This sounds like a great idea for advance publicity for a book launch, so I'll keep that in mind for the future. Meanwhile, I'm just going to enjoy two great countdown calendars.
And one more Advent calendar, this time for cat lovers. Georgia Dunn, the artist who created the Breaking Cat News webcomic, has an Advent calendar of the Breaking Cat News crew in various holiday garb on her Facebook page.
Have you come across any interesting means of counting down via a calendar or similar structure?