If you're willing to add some calories, oil. I got an oil sprayer. I fill it half with chili oil, half with olive oil; not too hot, but gives it a kick. Sprayed on, it doesn't put nearly as much in as being drizzled on. It helps make powdery stuff adhere to the popcorn, too.
I have a salt shaker of Flavacol, which is the "salt" part of what goes into movie theater popcorn.
Movie theaters use (or used, dunno if this has changed) palm oil. This can congeal at room temperature, so may need to be heated.
Powdered butter or powdered various sorts of cheese can be kept in the fridge and can just be sprinkled on.
Cinnamon and sugar can be sprinkled on.