There are over 1,500 calendar apps to choose from...
And you can track things I never would have dreamt to search....
You can track the moon, remember to pray, choose your baby's gender, clean your house, view a new photo each day, clean your house....
a great number of Advent Calendars.... for young and old.
The two I selected to share are
Advent 2012 is giving away a free app a day for the next 25 days.
I cannot advise on what you will receive, but I can note that I think it is a fun way to try a few new apps.
MagicSolver.com has done this for few years, and reviews indicate you will find something worthwhile in the countdown.
The Christmas Card Advent Calendar (for children)
Story Mouse allows young learners to make and email cards
featuring favorite storybook chracters.