I nerd out over food science. Figuring out why it's better to prepare a food one way over another way, the best way to store a food and why. Why Dutch processed cocoa powder for some things and not others. Baking. So much science. Learning why for all of the food things. Serious Eats, Cook's Illustrated, Bon Appetite, all my jam. Love love love.
Nail polishes and yarn make me want all of the colors, textures, glitters, etc. as appropriate for if it's nail polish or if it's yarn. I ogle hand dyed and/or spun yarn on Etsy and get stuck going down a rabbit hole of pretty fiber.
Books. Doesn't matter if it's a genre I tend to read or not. Libraries, book stores, second hand, etc. Love my Kindle, but love touching pages. New book smell. Vocabulary. Leather covers. Elegant fonts. I am jealous of Beast's library in the Disney Beauty and the Beast. I like to look at books even if I wouldn't likely read it. Love to actually read too, of course. Second hand places are fun, you never know what you'll find.