This e-print archive is the premier electronic source for most streams of research in physics, mathematics, computer science, nonlinear sciences, and quantitative biology. Currently this web searchable database provides access to a huge repository of freely accessible papers. ArXiv is operated and funded by Cornell University.
Physics Classroom: Concept Builders
Concept Builders is a series of interactive tutorials designed to help students understand and apply physics concepts. Each concept builders includes short tutorials related to the concept and is accompanied by learning goals.
Physics Flash Animations
This site provides Flash animations from different areas of physics. Topics covered include classical mechanics, electricity and magnetism, optics, quantum mechanics, and sound waves. All animations require Flash player which can be downloaded using a convenient link that is also provided.