In order to make a rendering look more realistic some additional maps are useful.

The [documentation](http://wiki.blender.org/index.php/Doc:2.6/Manual/Textures) lists: diffuse,specular displacement-maps .

I watched a video [tutorial The Secrets of Realistic Texturing](http://www.blenderguru.com/videos/the-secrets-of-realistic-texturing/) which uses a commercial tool. 

Are there any alternatives to calculate normal and displacement maps from an image texture, or can this also be achieved by some build-in transformations?

NOTE: As requested, this is related to image-textures that have been downloaded from a site like [cgtextures](http://www.cgtextures.com/) which are image-only and lack of normal- and displacement-maps.