Interested in seeing how the Blender Game Engine (GE) works? Well, BlenderNation has compiled a small list of available resources that feature various GE demos and tutorials just for those trying to learn more about using Blender for game and architectual development.
Blender Artists Forum contains several resources by artists such as blendgine, icesw, lemmy, Siegel, DanyAlejand, jrt, john, gargola, Abracsis, Amiganr, Doc Holiday, and many others. Also featured are Web Plugin games and stand alone games. There are quite a few tutorials as well.
Geneome's (Eugene) site has a good Rigid Body tutorial for those interested in learning more about how to use the rigid body physics engine in animations.
If you have any good repositories be sure to post them in your comments!