These online lectures are really useful to improve your knowledge:

TED all kinds of lectures:

http://www.youtube.com/TEDtalksDirector

Physics lectures and all other subjects:

http://videolectures.net/mit801f99_lewin_lec34/

About quantum computing:

http://www.youtube.com/watch?v=I56UugZ_8DI

Online courses from top scholars:

http://www.academicearth.org/

Full courses:

http://freescienceonline.blogspot.com/

Lectures:

http://forum-network.org/station/wgbh


Lectures from universities:

http://www.youtube.com/user/MIT

http://www.youtube.com/user/nptelhrd

http://www.youtube.com/user/stanforduniversity

http://www.youtube.com/user/ucberkeley

http://www.youtube.com/user/harvardbusiness

Please add your useful sources here. - in any language.

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