I'm not a fan of oranges but find myself tucking into a satsuma or two over Christmas - my dad was quite traditional about our Christmas stockings when we were growing up and always put an orange in there with the few small gifts that would fit in the stocking.
My friend was involved with a historical society and each Christmas she used to make me some wonderful Christmas decorations made with oranges - the era her branch of the society covered were brilliant at stuff like that, highly craft conscious and luckily they had to get their display stuff so perfect that there were plenty of items (equally perfect but discarded for some trivial reason) left over to distribute to very grateful friends! Sadly I haven't seen her this year and haven't the skill to reproduce her gorgeous creations, I really wish I'd taken photos last year to show you all but I didn't think about it.
My favourite item (or items) from last year were some gorgeous oranges which had been studded with cloves, it smelled divine and literally two oranges could scent the whole house. They were tied in intricate arrangements with ribbon and finished with a bow on the top for hanging, the full size oranges were too heavy for the Christmas tree but my friend toyed with the idea of making smaller versions using satsumas to hang from the tree - I don't know if she those this year but I wasn't sure it would work so well personally due to the peel being so much looser on a satsuma.
So yes, O is definitely for Orange in my Christmas A-Z - if only for the wonderful fragrance of these zesty/clove natural decorations.