This service provides databases with chemical information

[previously known as PDB - Protein Databank, Brookhaven National Laboratory]
The Research Collaboratory for Structural Bioinformatics (RCSB) is a non-profit consortium dedicated to improving our understanding of the function of biological systems through a study of 3-D biological macromolecular structure. RCSB integrates a variety of production-level data and software resources and shares research results and software.
The database includes some 3D data for oligonucleotides and tRNAs.

Free software for looking at molecular structures. It runs on Windows or Macintosh/PPC computers (also unix). You must download a free PDB data file for each molecule you wish to view. It is very fast: rotating a protein or DNA molecule shows its 3D structure.