Redbook
Examples from the "OpenGL Programming Guide".

Samples
Collection of simple programs helpful for testing an OpenGL implementation. Many have keyboard options (see source for details).

More Samples
More samples collected from a variety of places.

GLUT Samples
Samples that are included with the GLUT distribution.

Win32 tutorials
Windows 95/NT specific programs intended to be a tutorial for those getting started with OpenGL and Win32.