techniques

scene formats 

There really isn't a clear standard for 3d scene description formats.  There are many models available in older formats such as DXF (autocad) and 3DS, but those formats have many limitations, and are showing their age.

Newer formats are typically much more functional, but tend to be proprietary.  There are a fair number of candidates for a standard scene description formats, but none seems to have been widely adopted (and they tend to be rather complex).

tools

HDR environment maps

HDR stands for "High Dynamic Range". Environment maps using HDR formats (e.g., OpenEXR ) can offer a realistic representation of the light in an environment (with the "white" sun being many orders of magnitude brighter than a white table). Because of this HDR environment maps are useful for providing realistic lighting as well as providing a pretty backdrop for a scene.

  • One of the pioneers in making HDR environment maps is Paul Debevec .  There's a collection of classic HDR environment maps on his Light Probes page, and a very recently added page of very high-resolution HDR environment maps on his High Resolution Probes page.  The latter are fairly large (up to 45MB for a  single image, or hundreds of megabytes unpacked into memory!), but look quite fantastic.
  • A sampling of high-quality commercial HDR envmaps in the LightWorks HDRI Starter Collection (these seem free to use, but are intended for users of the LightWorks rendering suite).
  • A nice HDRI resources / tips page at the Cinema 4D Cafe.
  • Some free samples of Sachform's commercial HDR environment maps.  These have very obvious (in some views) watermarks, but are of very good quality and high-resolution.

models / textures / etc