Was reading the skeletor thread and it occurred to me that motorcycle helmets would actually do a lot of good for cyclists in preventing head and neck injuries (and death vs cars). Seems like overkill at first glance, but there's evidence to suggest that existing bike helmets do very little, other than to instill a false sense of security. Also, it's considered normal for scooter riders to wear one and they don't go much faster than bicycles. Another plus is that you won't need googles or safety glasses due to the full face shield.
Motorcycle helmets these days are pretty lightweight and well-ventilated; here's one with a carbon shell: