These links will take you directly to the portions of databases that contain materials relevant to Biology. However, this is by no means an exhaustive list. Feel free to explore the General Collections to find additional resources.
MERLOT II is a program of the California State University, in partnership with educational institutions, professional societies, and industries to provide a database of more than 40,000 materials related to a wide variety of subjects. These materials come in a variety of formats, including animations and simulations, assignments and quizzes/tests, case studies and reference materials, and open textbooks, journals, and articles.
Hippocampus offers educators a wide variety of multimedia content online, including videos, animations, and simulations. An additional feature offers educators the ability to create "playlists" for their students, which correlate specifically to their particular instruction material.