A helmet saved me in a face-first fall. The crushed area of the helmet was the part that covered my forehead.
I might not have been killed, but thinking abstractly might have been a problem after that.
Helmets are the cheapest insurance against catastrophic head injuries from a fall.
After ice-skating with my brother-in-law this summer, I wonder if skaters might benefit from a really dorky-looking helmet. I watched as my son fell on the ice and hit his face. My brother-in-law came to the rescue, and promptly fell backward while the back of his head bounced on the ice. Buy one get one free.