I have noticed that the 3D viewing program (Deep Exploration) i use to look at models and DDS textures, has an option to creat Normal maps from any texture.
So i gave it a go, i changed the image to greyscale, then inverted the texture, and finally converted to a normal map
If you want to try this yourself, you can download a demo version of Deep Exploration
Here
http://www.righthemisphere.com/products/dexp/index.htm
The results do work, but are a bit fuzzy,
I supose its because it creating the normal from a texture not real data
Try it out, see what you think ?
here is the preview
and here is the download
http://www.bt.homepage.btinternet.co.uk/images/Moon-Bump.jpg