Something missed in SRD rules or Pathfinder is the Tread Damage made by larger creatures to smaller... Like a Gargantuan Dragon treading with its feet a small halfling.
It's size and weight obviously affects the damage, and not by strenght
Does anybody use some house rules or any good ideas?
Natural attacks already include size and weight in their base damage, and the muscle to throw your mass around is included in strength. A dragon stepping on a halfling is its claw attack or tail swipe.
Note that dragons are a special case since they even have a special Crush attack to simulate standing on an enemy.