We normally use the following:
Fresh ground salt and pepper (favourite)
Castor Sugar
Parmesan
Bacon (v. unhealthy!)
Wasabi

When we have trouble making a topping stick, we use a little hot oil/butter and put it in a LARGE tupperware box with the popcorn and seasoning, pop the lid on and shake vigorously. The topping will stick and any left over can be scooped up.