Hey! It's nice to hear of another map fan.

My son is four and has enjoyed looking at our metro map since he was three. He especially loves the Key and finding all the points of interest.

And...he is into compasses, so looks for the N/S/E/W on every map.

(A jump-off of maps was the DMV driver's test booklet. It has lots of road signs.)

As for books on maps, our son has enjoyed, "Me on the Map" by Joan Sweeney (although probably too young for your eight year old).