I'm always saving empty spice and salt grinders for a vague "future use." Well, I finally know what that use is: I'm going to fill them with Doritos and grind delicious Dorito essence all over my food.
Now, of course it doesn't have to be Doritos; the above video from Tasting Table has quite a few suggestions for grindable goodness, both savoury and sweet, but you should consider Doritos. They may not be that great for you, but they are literally engineered to taste good, and who doesn't want Dorito-flavored popcorn? (Identify yourselves in the comments.)
Hack Your Pepper Grinder [Tasting Table]