Shade relief by time of day based on sun position

I'd like to see a dynamic shading feature that could show where the shade will be based on the suns position.  While looking at a Topo, you add Shade Relief, and then can move the sun based on time.  This would show you where the shadows will be for specific topographical features.

I like seeing this to help determine the best sleeping spots to either capture the early morning rays, or avoid them.  Also, helps determine potential snow field areas.