Genetic Science Learning Center http://gslc.genetics.utah.edu/
Intro to DNA Structure http://www.blc.arizona.edu/Molecular_Graphics/DNA_Structure/DNA_Tutorial.HTML
Journey into DNA http://www.pbs.org/wgbh/nova/genome/dna.html#
Create a DNA Fingerprint http://www.pbs.org/wgbh/nova/sheppard/analyze.html