In the world of computer generated imagery, textures are… kinda important. :) Painting good texture is an art by itself.
In his tutorial “Painting Hard Surface Textures“, Stefan Morell shows how you can create textures for, well, hard surfaces. He uses Photoshop in his example, but the technique is most likely adoptable to other applications.
Step by step he describes the process of creating color, texture, bump and reflection maps. The tutorial closes with some general tips to texturing, like required resolution, details and photo references.
(via Kreativrauschen *g*)