Lectures on-line

1. Free Online Course Materials | MIT OpenCourseWare

2. Free video lectures,Free Animations,Free Online Tests,Free e-book download links,Free Lecture Notes

3. CosmoLearning | Your Free Online School: Courses, Video Lectures, Documentaries, Images, Books and more

4. Personal and Historical Perspectives of Hans Bethe

5. TED: Ideas worth spreading