'Tis still the season of greeting cards in France. The French have the sensible custom of sending out Happy New Year (Bonne année) cards instead of Christmas cards, so you actually have time to write them. You can send them out until halfway through February.
Another pleasant old custom which is certainly observed in my family is the galette, or king-cake as we call it in Louisiana. Inside the cake is a fève, or "bean" (in Louisiana, a plastic baby), and whoever finds it in his or her piece of cake is crowned king or queen-- the galette is always sold with a small gold cardboard crown! In France, the fève used to be a real bean, but is now made of porcelain, and bakeries vie with each other to find interesting fèves, as there are many fève-collectors.