Source Code

AblazeSpace
OpenGL freeware and open-source games written in VisualC++
http://ablazespace.sourceforge.net/as-page/

ATI Developer source code
ATI Render Monkey, DirectX, OpenGL, MacOS and third parties samples.
http://ati.amd.com/developer/indexsc.html

The Code Project
Free source code and tutorials for OpenGL on Windows.
http://www.codeproject.com/KB/openGL/

3D Computer Graphics: Programs & Tutorials
OpenGL programs and tutorials
http://www.jimbrooks.org/web/opengl/

gewang.com
A site of self-contained opengl samples for teaching opengl and rendering techniques of various levels of difficulty (include well-documented source code).
http://www.gewang.com/projects/samples/opengl/

GLdomain.com
Demo scene and game development with OpenGL.
http://www.gldomain.com

Nate Robins - OpenGL
Coding examples, tutorials, and rendering techniques for OpenGL.
http://www.xmission.com/~nate/opengl.html

Objective CAML for Scientists: Visualization
Source code examples demonstrating the use of OpenGL from the OCaml programming language, from the book "Objective CAML for Scientists".
http://www.ffconsultancy.com/products/ocaml_for_scientists/visualisation/

OpenGL Programming in Delphi
Terrain rendering, utilities, sample OpenGL code and sources in Delphi.
http://arrowsoft.ifrance.com/arrowsoft/opengl.html

OpenGL stuff
A variety of interesting OpenGL related material by Paul Bourke.
http://local.wasp.uwa.edu.au/~pbourke/modelling_rendering/