Frozen Goodies - An advent calendar to get the chance to win daily prizes
Fantastical 2 - Fantastical, the Mac calendar app you'll enjoy using. Quickly create new events with natural language input and more.
25DaysOf - A customizable advent calendar, for everyone
Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
24 Ways - An advent calendar for web geeks
Simple Calendar - A simple calendar with events (optional recurring and reminders), week numbers and a customizable...