Basic Engineering and Sciences:
1. How Stuff Works
One of the best websites ever, one can pick up the fundamentals of how almost everything works, and no less, of how most engineered appliances and systems work. A good place for beginners and the curious alike.
2. Basics of Design Engineering
http://www.catalyst.uq.edu.au/designsurfer/basics.html
Mostly theoretical, but you should read through the pages. It's an excellent resource to help you understand design in engineering.
3. Engineer.com!
http://www.engineering.com/content/index.jsp?disciplineID=mechanical
Yes, its that simple. A very good interface.
3. Rock Engineering Fundamentals
http://www.grow.arizona.edu/rock/rock_eng_fundamentals/rockengfundamentals.shtml
Rock Engineering at Arizona State University. A very good website, that covers several resources on a very unique and interesting branch of Engineering.
4. The Civil Engineering Portal
http://www.icivilengineer.com/Structural_Engineering/Basics/
5. Chemical Engineering
5.1 Who is a Chemical Engineer?
http://www.glorifiedplumber.com/gp/Chemical%20Engineering.htm
Find out from a chemical engineer, who passionately writes about the field.
5.2 What is Chemical Engineering composed of?
http://www.geocities.com/Faisal_ChemicalEngineeringPage/Basics.html
A very good page, that tells you what you need to know to become a chemical engineer!
6. Marine Engineering
http://www.johnforester.com/Maritime/SEB2.htm
Do you know how steam engines work? Here is an interesting read.
7. Software Engineering
http://www.sju.edu/~jhodgson/se/softeng.html
Very basic, and little information, but useful for the beginner.