0.8 added a helmet to the shop that reduces fall damage. It's pretty expensive for what little difference it makes, though. Ragdolling reduces the damage by a lot more and it's free.
Does it reduce fall damage? As far as I know, the helmet just completely negates any ragdoll physics damage done to the head, you could be ragdolled flying at terminal velocity and be fine assuming you directly hit your head while wearing it.
