Cambridge Cluster Database - Low-energy configurations for atomic and molecular clusters bound by various potential energy functions. Images and Cartesian coordinates are supplied.
Molecular Models for Biochemistry - Pictures of the molecular structure of amino acids. Also features common properties of all amino acids, peptide structures, and a protein structure quiz.
Protein Data Bank - Three-dimensional structures of biological macromolecules. Also includes newsletters and a description of the Protein Data Bank file format.