These are the advent and holiday calendars I follow this year:

• 24 ways to impress your friends – Web design and development articles and tutorials for advent
• 24 Accessibility – 24 days of digital accessibility gifts during the season of giving and sharing
• 24 Pull Requests – Giving back little gifts of code for Christmas
• UXmas – An advent calendar for UX folk
• Perl Advent Calendar 2018
• Advent of Code 2018
• Performance Calendar – The speed geek’s favorite time of the year

If you know any interesting holiday or advent calendars, please post them in the comments.