Biology

This site describes itself as "an ambitious project to organize and make available via the Internet virtually all information about life present on Earth." They plan to have a page on each organism on earth.

Overview of endangered species, with links to sections on extinct, threatened, and recovered species. (The next entry is better for a current list.)

Considered the most complete and up-to-date list of threatened plants and animals. Entries are rated by how endangered they are. From the International Union for Conservation of Nature and Natural Resources. (The above entry is better for a general overview of the topic.)

"Database of animal natural history, distribution, classification, and conservation biology" from the Univ. of Michigan.

Beautiful photos and basic information about insects and spiders. You can browse by type of bug or use the table of contents for an alphabetical listing.

A nonprofit conservation organization that has research information on many invertebrates. Look at the "Publications" and the "Invertebrates" areas.

From the US Dept. of Agriculture. Vascular plants, bryophytes, lichens.

Large collection of close-ups of plant structures, including some animations. From the University of Miami.

Great photos of over 400 species of trees. Browse through the collection by family or use the search at the bottom of the screen.

Information from the US Dept. of Agriculture on organic and sustainable farming practices. Covers growing crops, pest management, water management, and more.