Excellent website for Math Lessons for K-8 grades. State Standards are available along with Algebra, Geometry, Trigonometry, Calculus, and Statistics tutorials free to students. Good website to link to a Math teacher’s website.
ClassTools.net: Create free educational games, quizzes, activities and diagrams in seconds and then post them to your own blog or website. No charge, no signup required. Templates abound in all areas of the curriculum. Students can design multiple interactive games from the same set of questions and answers. Newest template is “Fakebook” (a Facebook template that allows teachers and students to create imaginary profile pages for study purposes for book characters, historical people, chart the plot of a book, the development of a character, a series of historical events, the debates and relationships between people, and so on.)
Solar System Scope: Interactive, 3D model of solar system planets and night sky.
PhET : Fun, interactive simulations of physical phenomena–physics, chemistry, earth science, physical science and math simulations– from the PhET project at the University of Colorado. These simulations can run online, download them or even embed them in your website for student use.