I would like to take this moment to mention some of the other sites running with the technical-advent theme:
- 24 Pull Requests - "a yearly initiative to encourage developers around the world to send a pull request every day in December up to Xmas"
- 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 2012
- Web Advent
Update: Len Jaffe maintains a collection of programming related advent calendars over on his site (don't be frightened by the fact that it's called Perl Advent Planet - all kinds of programming languages have a home there). From there come the following two:
- Perl 6 Advent Calendar (if you didn't hear - Perl 6 is a completely different language from Perl 5!)
- SysAdvent (not only) for sysadmins