Photography
Yann Arthus Bertrand is well-known for his photos of the earth from above. You may have seen his books, one of which AndrĂ© and I got as a wedding present. The site also offers some of Bertrand’s photos as desktop wallpapers.
Mathematics online
maths online: maths links and online tools is a collection of more than 60 tools and links, including The Integrator, the function plotter, or the HTML formula tool.
Physics
I should probably take a closer look at Newton’s Aquarium, which is “an interactive physics package that helps students visualize and understand Newton’s Law of Universal Gravitation. While creating and exploring their own solar systems, students encounter the core concepts in classical physics.”
Link via Schockwellenreiter.