I like my giro 9 ski helmet. www.giro.com It has more protection around the temples and in the rear of the head. The back of the helmet comes down around ear level.

I feel much safer wearing my ski helmet than my bike helmet. It covers more and has more padding. A ski helmet is probably not certified for bicycling use, and it would be really warm for most riders since it's meant for colder weather. It is vented and i don't usually have problems with it in "spring" conditions ~45 deg. F.

Maybe there's a way to adapt the better coverage/padding into a more efficient venting design...

bk