http://webexhibits.org is a very art-student friendly collection of educational web galleries. (As a matter of fact, it was a student who showed me the site.) It is a collaboration with IDEA (see below) and museums worldwide, including the National Gallery of Art. Some of the chapters are: Color Vision and Art (with several interactive activities); Pigments through the Ages and Van Gogh's letters.
http://idea.org is the site from which the above site originated. Here are a few paragraphs from their intro: "The Institute for Dynamic Educational Advancement (IDEA) is a nonprofit organization that takes bold ideas about facilitating and broadening the learning process and transforms them into information systems that are then shared with others who share our passion for interactive learning.
IDEA arose out of the belief that there should be no barriers between people and computers. Technology is now advanced enough to adapt to the ways people naturally think and interact with the world. The user’s experience with technology should be personalized, interactive, and intuitive, so that the tools add breadth and depth to the information presented, and stimulate creative thought. Innovative strategies built into the technology can help people from all walks of life maximize their potential."
Big goals. Although the IDEA site is designed to help people who are designing educational websites, parts of it are useful to all educators, from some theories of learning to effective evaluation of your own work, to a color blindness simulator. If you are trying to create an educational interactive website, this is a resource you shouldn't pass over.
Hopefully both these sites will continue growing.