A setup made up of twelve cloud puffs (localised cloud layers) with differently animated cloud fractal shaders. Nitpicking myself, if you look closely there's a visible (smooth) transition between the puffs.
Nevertheless I like it, but unfortunately it's quite useless unless the smoke source is exactly at 0,0,0.
So this is a good example for the need of grouping things and linking this group to a dummy, which can be positioned anywhere in the scene without having to type in different values for each item.
This would be an incredible improvement.