It hasn't been really cold here for a while but I saw a biker in Rotterdam a few years ago who had 'mittens' attached to his handle bars. You simply insert your bare hands inside these 'mittens' and shield your hands from the cold while biking.

From what I understand these 'mittens' are somewhat common for motorcycles or motorbikes(?). At any rate. I thought that was a good idea and have yet to come across this in any bike shop.