This tutorial will show you how to make a nice looking map.
Map:
1. New Document: 650x650 Pixels
2. "Filter > Render > Clouds"
3. "filter > Render > Difference Clouds"
4. Continually Press "Ctrl+F" until you get something like this (I Pressed it about 15 times)

5. Now Press "Ctrl+I" to invert the colors.

6. "Filter > Sketch > Note Paper" (Image Balance: 33 | Graininess: 10 | Relief: 16)

7. Using the "Magic Wand Tool" Select the Lighter Spots of the canvas. (Hold Shift while clicking, to add spots to your selection.) It should look something like this when your done.

8. Now Press "Ctrl+B" and use these settings:
For "Shadows" :
Yellow: 100
For "Midtones" :
Yellow: 100

9. Now Do the same, except this time, select all of the darker areas. So it should look like this:

10. Now before adding color to it, go "Filter > Sketch > Chrome" (Detail: 5 | Smoothness: 0)

11. Now while it's still selected, right+click inside the selection, and choose "Layer Via Copy" (This will put the chrome part on its own layer) Now You Can Deselect, and this is what it should look like.

12. Now on the new copied layer, press "Ctrl+U" and use these settings:

13. It should now look something like this:

14. Now Make a new layer (Layer > New Layer) And fill that layer with Black.
15. Now Set its Blending Mode to "Overlay"

And now it should look something like this:

16. Now take your paintbrush tool, and with a size "83" and a hardness of "0" draw around the border, until you get something like this:

And There You Have it! A nice looking map!
-Scott