Most interesting ways I have gotten THC into my system:
A tincture, made with PGA, I used an eyedropper to add drops to everything from coffee to mixed drinks.
I also used a tincture wrap for localized pain, that was interesting though not very effective in my opinion.
I would think a gravity counts as a normal way, I mean who grew up and didn't make multiple gravity bongs, we did stupid ones (like 5 gallon buckets in a 55 gallon drum), and effective nice ones. Waterfalls are another good way, but pretty normal I would think.
Gas mask is interesting as well, I have done some with fans and without
A Hookah is one of my personal favorite ways, about a three hose with a few friends, just chill for an hour and smoke at your leisure.
I learned growing up that you can make smoking pieces out of everything from a can of soup to an apple, or water bottle.
Smoking BHO is quite an interesting experience as well, though I personally don't care for the taste, and the buzz is not just extreme, but different as well, can't quite put my finger on it. Perhaps it is the lack of presence of some other cannibanoids.