Cells Alive -- Awesome site with great videos of cell division. http://www.cellsalive.com/
MEGACELL http://nobelprize.org/educational_games/medicine/2001/
CONTROL OF CELL http://nobelprize.org/educational_games/medicine/2001/
An explanation of diffusion. http://www.biologycorner.com/bio1/diffusion.html
Microscope Parts Practice http://www.biologycorner.com/microquiz/index.html#
Biology of Macromolecules http://www.bbc.co.uk/education/asguru/biology/02biologicalmolecules/index.shtml
Help on cell organelles http://cellbio.utmb.edu/cellbio/
Explore Microbes http://www.microbe.org/