Here's a quick list of 3d assets that have been created, since I use Maya 2008 most of the files are in that format. David Hickson has made some good stuff for Blender too. There's some making of videos here.

OBJ
Arrow
A simple 3d arrow in OBJ format.

Manipulator.obj and Manipulator.mtl
Polygon versions of Move, Rotate and Scale Manipulators in OBJ format.

Camera Model
A Polygon Camera in OBJ format

MAYA (2008) files
Camera, Lights and Shader setup
This is the camera and light and shader setup I use, it's very simple.  Feel free to play around with the shaders if you don't like them.  If you like you can add the background.tif to the camera, it's found in the Fundamental Style Guide .zip Pack.  I usually comp in After Effects so I add the BG there.

Camera Only
The Maya Camera that I use, has resolution gate on, 50 lens and gimbal working properly 

Maya Lights Only
A feww directional lights I use to light the scene, very simple

Arrow
A simple arrow in MB format

Manipulators
Move Rotate and Scale manipulators in MB format.  The Scale has a little rig attached too.

Camera Model
A Polygon Camera in MB format

BLENDER

Blender Scene Setup
David Hickson has created this great blender file which has a basic grid, lights and shaders ready to go.

MAYA SCENE FILES OF MOVIES I'VE MADE
Here are the scene files of some of the videos I've made, should be pretty informative on how they are done.  Usually they take 1 - 2 weeks to create.

The Polygon 10 MB (Maya .mb)

Primitives (Thorny Devil getting Built) 2.2 MB (Maya .mb)

Vertex Normals 3.5 MB (Maya .mb)

Objects 5.9 MB (Maya .mb)

Hierachies Coords (this is a WIP) 1.1 MB (Maya .mb)

3DS MAX Scene Files

Greg Petchkovsky's Max Scene file for his Subdivision Surface Artifacts video