3D Studio Max:

3D Studio Max

Render-Engines:

Brazil
Final Render
Maxwell
Maxwell Knowledge Center
Mental Ray
Messiah
Renderman
V-Ray

3D Community:

3D Total
3D Cafe
3D Luvr

Tutorials:

Tutorialfind
Tutorialfinder

Textures, Meshes, Skies, Maps:

Meshfactory
1000 Skies
Earth Observatory
Space Graphics

Other 3D Software Packages:

Cinema 4D (Maxxon)
Maya (Alias-Wavefront)
Lightwave (Newtec)
Blender (Open Source)
XSI (Softimage)

Modeling:

Setting up Reference Planes [Tutorials/Blueprints Setup]