Fun Science Extras from Discovery Education: http://www.youngscientistchallenge.com/checkitout/whelmers.html
Science of Everyday Life: http://www.scienceofeverydaylife.com/
Science 360: http://science360.gov/files/
Nova: http://www.pbs.org/wgbh/nova/
PBS: http://www.pbs.org/
Virtual Labs from Howard Hughes Medical: http://www.hhmi.org/biointeractive/vlabs/
LabBench by Pearson: http://www.phschool.com/science/biology_place/labbench/index.html
Wonderville: http://www.wonderville.ca/asset/csi-techniques