Dr. Valentine
this is interesting to me because I have recently been compiling maps for my own nerdy roleplaying uses!
How exactly did you achieve that fold distortion effect? It's quite nice.
Layer blending effects in Photoshoppe, mostly. Each fold-line is first made using the Line tool, and a round, hard-edged brush with Shape Dynamics > Size Jitter set to about 50%, Scattering > Scatter (both axes) at about 70%, Brush Tip Shape > Spacing at about 80%, and Brush Opacity at about 60%.
Draw your crease-lines on a new layer above all the other layers using the Line Tool, and Stroke Path with Brush once or twice, using the above brush settings loaded with white. Duplicate the layer.
Top layer (which'll be the faded/lighter bit of the crease), set the layer blending properties to Master Opacity 80%, Layer Blending Mode to Luminosity.
For the layer below that (which'll be the darkened bit), hit Ctrl+I to invert the black and white; use the Gaussian Blur filter to blur the colour out a bunch, and set Layer Blending Mode to Soft Light. You might want to duplicate this layer a couple of times to get the right colour, especially round the edges of the map.
And that's about it, going from inspecting my .psd files to unravel what I did.
biggrin