This is a project I assembled in UDK. It's made using a combination of modular static meshes, BSPs and props.
The majority of the normal maps are made from baking high poly meshes to low, with use of nDo to provide some high frequency detail. Almost all of the textures are painted, with minimal use of photo source overlays.
In some instances the alpha of the Diffuse or Specular would be used to create a mask for the purposes of cube mapping, using the Spec Power channel, or using the emmisive channel in UDK's materail editor. None of the textures used exceeded 1024x1024.