I was hit by a car in 1978 -- no helmet -- skull fracture and a number of other not-very-fun injuries. Started riding again with a Bell Biker. These days I use a Specialized Prevail -- super light and the least horrible sweat-producer of any helmet I've ever worn.
Only place/time I do not wear one now (edit: while on a bike!) is riding around in towns in the Netherlands when I go to visit my relatives there -- no one other than hard core roadies there wear one, and motorists and dogs are exceptionally well trained and respect bicycles, plus the infrastructure is terrific.