I am a microwave pop corn gal right now but when I was a kid we would use the air popper and have it pop into a big brown paper bag then take the melted butter and pour it in while shaking the bag of pop corn was always evenly distributed and yummy :D
If you put some crisp bacon in a food processer it makes a wonderful "salt" for your popcorn. I put the butter and bacon in layers and stir together. Yummy stuff!