As every year there are several holiday calendars.
The ones I follow this year are:
- 24 Ways – Web design and development articles and tutorials for advent
- MDN Holidays calendar by Chris Heilmann
- 24 Pull Requests – Giving back little gifts of code for Christmas
- 25 Days of Making – faberdashery
There are two more in German:
Another one is: Perl Advent Calendar 2013 – twenty four merry days of Perl