I do a lot of the stuff mentioned. Nostolgia, daydreaming. I go on random binges where I meticulously alphabetize books or movies or clean my iTunes for hours at a time, like people have said.
Another example, whenever I go to the TVTropes website it's like a goddamn Si party. I like making lists of silly but similar things not unlike what they do at TVTropes, or comparing people I know or me and my friends group dynamics to characters/dynamics from books, shows or movies.