USDA PLANTS National Database- standardized information about the vascular plants, mosses, liverworts, hornworts, and lichens of the U.S. and its territories.
Tree of Life Web Project - Information about biodiversity compiled by hundreds of contributors. Its goal is to contain an information page for every species and every group of organisms, living or extinct.
Understanding Evolution - General information about evolution from the University of California Museum of Paleontology.
Why Evolution is True - Jerry Coyne posts about science, animals, religion, politics, and more.