For those who enjoy using Photoshop to learn some techniques that are cool to know, here is a link to an excellent tutorial:click here
The tutorial is better than anything I could print here.
And if you would like to use the two photos that the instructor uses in the tutorial, here they are:The FaceRock Texture
Most Photoshop users will not use a displacement map very often. However, it's a neat tool to have if you ever need it.
You may post your results in this thread. We would enjoy seeing your creation and give it some love too!