Unfortunately, too many of the English language math textbooks that students see on a daily basis are written exclusively by professional educators without any serious input from mathematicians. As a result, these books are too much about teaching procedures and not enough about inspiring future mathematicians and scientists. At the other extreme, textbooks (usually at the college level) written by mathematicians tend to be dry and extremely dense. They may present all of the necessary definitions, lemmas, and theorems, but there is not enough room left for applications.
Plus Magazine, a University of Cambridge project is an attempt to correct this situation. It is an online publication that features articles, podcasts, book reviews, and news stories that makes mathematics relevant to those who are don’t grasp its importance and it is a collaboration between full-time educators and full-time researchers and practitioners of mathematics. You can find an article on why the violin is so hard to play and learn about the research of a recent Abel Prize winner (one of the top awards for mathematical research). The site also includes a collection of interesting nonstandard math problems and quite a bit of the content is related to physics. This should be a useful resource both for teachers and high school students.