Google Maps Layers Anyone?

I think that the thing that would make Google Maps very useful is
layers.

Just like in Photoshop, you could create a layer and add specific
information on it. You would be able to have multiple layers, each
with its own information. Why would this be useful? Lets say you are
trying to decide between two different routes, and you want to compare
them. With layers that would be easy.

An essential feature of layers would have to be adding specific
addresses. I think that being able to add an individual location to
the layer (or multiple locations). Then you could overlay a route on
one layer, and on another layer you could have all of the local bus
stops.

I think that this idea would really change the way people use google
maps, and it would make it more usable.