Order of Magnitude Estimation Book - Very readable ebook about the value of estimation and plenty of practice
(type: web.stanford.edu/class/ee353/SanjoyMahajanIntro-01-1.pdf into address windo if link does not work)
AAPT Physics Photo Contest - Into Photography? Take a photo and explain the physics displayed.
Hyper Physics by Georgia State University Physics and Astronomy Dept Fantastic summaries of just about every topic within physics. Great concept maps to help you develop your understand of the domain of knowledge known as physics.
Some beautiful chemistry vidoes:
Comprehensive list of chemistry careers compiled by the American Chemical Society
The Subdivisions of Chemistry called Areas of Chemistry and Areas of Applied Chemistry