It's the Christian Seasons Calendar.
Beyond personal and family use, this would be a pretty neat gift for anyone in your life who followed or was interested in following the liturgical calendar
The basic concept of the calendar is fairly straightforward. Rather than the year beginning on January 1st and then having days grouped into twelve months, the Christian Seasons Calendar starts with the first day of the liturgical year (the first Sunday of Advent) and then groups dates under the liturgical seasons. You can see the layout here. And some pretty big endorsements here.
What is nifty about the calendar is that you can still use it as a secular calendar. That is, you can quickly look at it and see that, say, today is Tuesday March 5th. But you'd also quickly note that March 5th is the Third Week of Lent. Basically, the liturgical structure is imposed upon the secular calendar breaking it up, not into months, but into liturgical seasons with the number of days for each season varying in length depending upon how long the season lasts. Thus, rather than having 12 months/pages with roughly 30 days per page, Advent has twenty-four days on its page. Christmas has twelve days. Lent has forty days. Holy Week has seven days. And so on. You still have and can follow the secular days and months, but the organizing structure is liturgical in nature. What grabs your eye in not the month you are in (though that's readily available), but the liturgical season you are in.