The Light Cone: An Illuminating Introduction to Relativity
Syracuse University: The Light Cone
http://www.phy.syr.edu/courses/modules/LIGHTCONE/

The Principles of Yarn Texturing
Production of DTY stretch yarn on single heater false twisting machines
http://www.polyspintex.com/ups/text01.htm

Supply and Demand Principles
Explains basic principles of supply and demand curves.
http://members.tripod.com/~GOPcapitalist/supply.html

IMB Jena Image Library
Experimental determination of biopolymer structures Determination of secondary structure in proteins by other methods. Primarily by NMR methods.
http://www.imb-jena.de/ImgLibDoc/StructureDetermination/

Build Your Own Forth
Describes, in simple terms, the basic principles underlying the implementation of any Forth.
http://www.figuk.plus.com/byof.htm

Nondestructive Material Testing with Ultrasonics
Introduction to the Basic Principles (Krautkrämer, NDt-net)
http://www.ndt.net/article/v05n09/berke/berke1.htm

Applied Thermodynamics
Applied Thermodynamics, Energy, Power Plant, Combustion, Heat, Air Conditioning, Turbine, Pump, Condenser, Heat Exchanger
http://www.taftan.com/thermodynamics/

Electronic Theory Forum
Electronic Theory - Basic principles, ideas, concepts, laws, and formulas behind electronics.
http://www.electro-tech-online.com/electronic-theory/

CatEdu
Math and science software for k-12 or home school students which uses animation to teach the basic sciences (physics, chemistry, math, science).
http://www.catedu.com/

Math Notes
Mail order material that contains songs books to help students learn and remember basic principles.
http://mathsongs.com/