The Khan Academy Videos on YouTube which have been recorded by Salman Khan.
The Stanford School of Medicine Lectures on human biology, health and disease, medical research, and health care. The lectures are available through iTunes, YouTube, and on the Stanford Mini Med School website.
"The Digital Morphology library is a dynamic archive of information on digital morphology and high-resolution X-ray computed tomography of biological specimens. Browse through the site and see spectacular imagery and animations and details on the morphology of many representatives of the Earth's biota.
The Encyclopedia of Life is a database that aims to have an electronic image of each species of organism to be found on the planet. Best results are obtained when searched by scientific name.
Microscope imaging station From Exploratorium
Online Biology Book The 42 chapters in this textbook cover cells, cell structure and function (meiosis & mitosis), mammalian and plant physiology, genetics and evolution, diversity and classification.