At University of Geneva ExPASy WWW Molecular Biology Server.

RasMol is free molecular visualization software developed at the University of Edinburgh's Biocomputing Research Unit and the Biomolecular Structure Department at Glaxo Research and Development, Greenford, UK. It is an educational and research tool that reads molecular coordinate files and interactively displays the 3-dimensional structure of DNA, proteins and smaller molecules. Allows simultaneous display of NMR models. It runs on Windows or Macintosh/PPC computers (also unix).