Here are the ones I think are really good in my Technique sub-folder:
A Tedious Explanation of the
f/stop
A Tedious Explanation of the f/stop
Mark Roberts' Online Course on digital photography - Pixels to Pictures (step-by-step)
Pixels to Pictures: Mark Roberts presentation on the basics of digital imaging and photography
Pretty Comprehensive Webpage on Using a Digital Camera
Using Your Digital Camera-Contents
For those of us having trouble letting go of 43mm diagonal
Felix Grant: The Growlery: A replacement for camera lens focal lengths
The syllabus for a University of Missouri - St. Louis Photography Course - lots of great camera and photography history and fundamental background, composition, light and post-processing. I don't know how long this will stay up - the course is currently in session a/o April, 2008 - so read it now (I'd say print it but it is clearly copyrighted).
http://huckfin.org/art172/index.html
My fav:
A series of really neat articles on composition, including the Golden Ratio (nautilus shell and the Fibonacci series - I am a statistical analyst in securities markets and math is geeky cool), a landscape composition article for painters and a composition tester.
Photography Composition Articles: Golden Ratio, Rule of Thirds, Golden Mean, Golden Section.
Paul