Let's see there's the not surprising tea pots and tea cups (some are decorative things of the genre most are functional), though I've had to curtail this hobby lately due to space and money issues.
Then there's books, I've got manga, comics, fantasy, sci-fi, language, science, gardening, herbalism, cooking and mythology for the big subjects.
I also have a box of foreign coins. I refer to it as my travel wish box. I have this personal superstition that if I have currency from the place eventually I'll visit there.