Biology/Nature
- WWW Virtual Library of Cell Biology
- Virtual Library - Developmental Biology
- Biodiversity Heritage Library
- eNature.com Field Guides -- Audubon Field Guides Online
- E-Print-Network
- Online Medical and Science Dictionaries from MedBioWorld (links to many online dictionaries)
- Digital Morphology (part of the National Science Foundation Digital Libraries Initiative)--unique 2D and 3D visualizations of the internal and external structure of living and extinct vertebrates, and a growing number of 'invertebrates'
- science.gov -- U.S. government science and technology databases
- Encyclopedia of Life --
a guide to approximately 1.8 million known species (in progress)