http://www.gamedev.net/reference/articles/article1212.asp
http://www.gamedev.net/reference/articles/article1088.asp
http://gpwiki.org/index.php/3D:Backface_Culling
http://www.cs.unc.edu/~zhangh/backface.html
http://www.gamasutra.com/features/19990806/compact_backface_culling_01.htm
backface culling can be performed for any point on each polygon, and does not require normalization.