in europe we see more and more such maps being established. there is an online map available for tyrol (western austria, innsbruck area ) that shows avapanche-prone gradients in 5-degree steps with a coulour code, that is 30plus, 35plus, 40plus etc. : www.lawinte.at
in switzerland, more and more of the anyways excellent 1:50.000 topographic maps become available with terrain above 30deg. marked red. many important regions such as davos are already availble.
i find these things super useful, especially because the off-piste concept in europe is different, to say the least. the fact that groomed runs are open does not say anything about avy danger in the neighbouring slopes. consequently, a serious and responsible offpiste skier must engange in avalanche-risk managment almost all of the time, and that is where it becomes handy to know the pitch of the terrain.