´╗┐The Naked Scientists...enjoy podcasts on topical science issues, kitchen cupboard experiments, astronomy, news and views!
http://www.thenakedscientists.com/

HowStuffWorks
http://www.howstuffworks.com/

Discovery Channel
http://dsc.discovery.com/

NASA
http://www.nasa.gov/

Planet Science
http://www.planet-science.com/categories/over-11s.aspx

Science Museum
http://www.sciencemuseum.org.uk/

The National Museum of Science and Industry
http://www.nmsi.ac.uk/index.asp?flash=yes

Doc Brown
http://www.docbrown.info/

NT Science
http://www.ntscience.co.uk/

CGP Revision - KS3
http://www.cgpbooks.co.uk/pages/interactive_ks3_science.asp

CGP Revision - KS4
http://www.cgpbooks.co.uk/pages/interactive_gcse_science.asp

Science News for kids
http://www.sciencenews.org/view/interest/id/3/topic/Science_News_For_Kids

Science News
http://www.sciencenews.org/