When I have an object and I dupe it, when I go to edit any of the objects I duped (including the master) it says "do you want to edit the master or create a new one?" If I change the master then all the dupes change also. This works with both geometry and textures. Just remember tho, if you ever changed one object by saying create new master then that object is no longer tied to the other objects. I just used this technique in the animation I am working on. I had duplicated a spline about 200 times and I needed to make a texture change. I selected "Edit the Master" at the warning box when I went into the texture room and all the objects changed to the new texture. btw: I'm excited...I think in like 4-5 days my animation will be done...Wahoo!