Living Language Daily Calendar
If you're looking for a desk calendar (one day per page) that will help you with your French, you might want to buy the Living Language desk calendar. It doesn't list all the holidays in France, much less the rest of the French speaking world. (For example, Bastille Day isn't mentioned.) But it does give you a word that may be new to you on most days.
As an example, today's word is le doute. It provides a pronunciation, definition ("doubt"), and a phrase that includes the word.
Dans le doute, abstiens-toi
When in doubt, don't.
(lit. In the doubt, abstain yourself.)
(I don't remember seeing the word le doute in my French Tree.)
Both Saturday and Sunday share the same page. Also, there's a cultural or historical note (in English) around the fifteenth and last day of each month. The upcoming one for January 15 discusses the Euro as French currency. (I'm old enough to remember the French Franc, so this is interesting to me. For those of you who were born after the switch to the Euro, you may be less interested.)
This would be an interesting supplement to Duolingo, if you're interested.
From reading the reviews on Amazon, it looks like each year's calendar is different, so you could get it again the next year and keep learning new words. Living Language also has desk calendars for German, Italian, and Spanish.
The bad news is that it doesn't have pretty pictures, just words.
That sounds really useful, good suggestion!
I've been doing something similar with using the French Republican calender as a way to pick up some vocab. Each day is dedicated to something from nature and/or agriculture, today it's an easy one, le lapin. I like how seasonal it is, and have been adding photos to cards in Anki - I hope I might learn to recognise more plants as well as learning the vocab. To me, the months in French are things like Nivose, Frimaire, Fructidor, I don't even know any others yet! XD So maybe I could do with using a modern calender, too!