A great app for iOS devices that allows teachers to set up grade books. I use it to grade homework for completion simply by walking around the room with my ipad.

Wolfram|Alpha is more than a search engine. It gives you access to the world's facts and data and calculates answers across a range of topics, including science, nutrition, history, geography, engineering, mathematics, linguistics, sports, finance, music... This is a great review site for students. I tend to use it as a refresher for algebra for my physics students. Care must be taken however that they don't use it as a cheating shortcut for math courses.

Part One Update : Part Two has been posted. Click here to read it It is a fact universally ackowledged that Internet has radically changed the way we percieve of the world. Reality has been supplanted by virtual reality and geographical borders have dissolved to give birth to a highly interwired world where the information travels both poles in a matter of a click.

A Multimedia Tour of the Solar System: one star, eight planets, and more This website is an overview of the history, mythology, and current scientific knowledge of the planets, moons and other objects in our solar system. Each page has our text and NASA's images, some have sounds and movies, most provide references to additional related information.

Great site with a lot of simulations/games on mechanics topics

The ComPADRE Pathway, a part of the National Science Digital Library, is a network of resource collections supporting teachers and students in Physics and Astronomy.