Oh, I just remembered, another useful tool in GIMP when making bump maps, is the Gaussian blur. After I get the map to look how I want it/am getting the affect I am looking for, apply a Gaussian blur around factor 0.4-0.6 and see if you don't like it even more. I have used this tool extensively to remove pixelation from the bump maps for the subs interior. Just thought I would let you know.