For a few years now web developers around the world have celebrated Saturnalia Christmas with advent calendars covering topics related to the web. Some come and go, but you'll probably recognize a few regulars on this list.
I may have missed some, so please pass them along if you know of any. For those I know are not returning, I have listed them at the end.
1. 24 Ways
24 Ways, the one that most of this think about for web development calendars, is back again. It's been going strong since 2005 and based on its history this year should have some good articles.
2. Perl Advent Calendar
Perl Advent Calendar goes all the way back to 2000 (and back then looked a bit more like a traditional advent calendar, too) and has been dispensing tips for Perl developers ever since.
3. 24 Jours de Web
24 Jours de Web is starting its second year as an advent calendar for web folk. Written in French, it is clearly primarily targeted at French speakers, but a round of Google Translate will open it up to far more readers (like me).
4. UXmas
UXmas is an advent calendar aimed at the user experience community. Coming from Australia, American readers may be thrown just a bit by the schedule. The calendar promises everything from sketches, to articles, to tools, to videos.
5. Webkrauts
Webkrauts has an all German advent calendar, and it also dates back to 2005. It covers general web topics, but being in all-German readers like me will benefit from a Google Translate version of the page.
6. 12 Devs of Xmas
12 Devs of Xmas will also start the day after Christmas and go for 12 days from then. When all the other calendars have wrapped up, you'll still have one to read. The site is silent on its return, but this tweet suggests it's gotten writers and has a plan.
7. Freelancember
Freelancember 2013 is targeted squarely at freelancers. Its daily entries will consist of downloadable gifts in the form of PDF worksheets. Think of this as less about web-tech and more about MadLibs for projects. It has last year's calendar there as well, and so far (as of December 1) I cannot tell the calendar will just be a repeat of last year.
8. Mozilla Developer Network Holidays calendar
Mozilla Developer Network Holidays calendar includes brief links to resources or demos and suggests that you can edit them (if they are MDN resources). It doesn't link to previous years, but you can just hack the URL.
9. SysAdvent
SysAdvent is targeted to systems administrators, but there is a some cross-over to web developers. It has posts dating back to 2008 (and yet I missed it in last year's collection), so there is plenty of good material there if you're too impatient to wait for each day to be revealed.
10. Web Accessibility Advent Calendar 2013
Web Accessibility Advent Calendar 2013 is in Japanese, and thanks to the wonderful powers of Google Translate, I can tell you that it is a calendar to make the talk about Web accessibility (based on this statement: Webアクセシビリティに関する話題でつくるカレンダーです。
). If you know Japanese, I welcome any corrections. The site Adventar.org appears to host other advent calendars, some about web technologies, some about ramen.
Not Returning
A handful of calendars aren't returning this year (so far), but in most cases content from previous years is still available. These include Font Deck's Adfont Calendar (which also skipped 2012), the Fronteers advent calendar (in Dutch, and also skipped 2012), Web Advent (it's taking a year off), Performance Calendar, HTML & CSS Advent (this is the 2012 calendar), She Said It (no access to old calendar), 12 Days of Podcasts (or at least there is no indication on its site or Twitter).
Not Web Related
ScienceGeek Advent Calendar Extravaganza is not web-related at all, and frankly it isn't promoted nor is it tagged (although I linked to “special” since that tag had the first day and nothing else). It is, however, probably going to be neat stuff given the first day is a giant image of the Christmas Tree Cluster.