Programming advent calendars are posts/articles for a particular topic posted daily between the 1st and 24th of December. They are modeled on the advent calendars received by children on some countries which contain 24 doors for the 24 days of advent and behind each door is a piece of chocolate or other surprise which the child gets on the particular day.
Here is the list of programming related advent calendars for 2013 (if you know of more, leave a comment and I'll update the list):
- 24 ways - "is the advent calendar for web geeks. Each day throughout December we publish a daily dose of web design and development goodness to bring you all a little Christmas cheer"
- The Perl Advent Calendar 2013
- Perl 6 Advent Calendar (if you didn't hear - Perl 6 is a completely different language from Perl 5!)
- SysAdvent (not only) for sysadmins
- Performance Calendar Learn all about web performance. (Primarily focused on frontend technologies.)
- UXmas UX is for everyone. Brush up on the topic this December.
- Go Advent - the go(lang) advent calendar
- 24 Pull Requests - "a yearly initiative to encourage developers around the world to send a pull request every day in December up to Xmas"