Originally Posted by
Shimagnolo
Take a look at helmets like the Giro Fuse Ski Helmet. The GF has one.
It has a set of vents much like a bike helmet, with a sliding button which opens/closes the vents.
Giro fuse is the one I use for winter, under 20F. It's remarkably warm. I keep the vents open almost all the time. when it get's down to 0F I add a thin balaclava. Oh and it would be hard to mount a light on though.