RasMol

RasMol is a molecular visualization program for displaying and analysing molecular systems in 3-D. Details of the latest release (2.7.5) can be found on the pages RasMol or OpenRasMol (both seem to be the same page).

Jmol

On the Molecular Visualization Freeware page there seems to be a tendency to recommend the use of Jmol as a more modern alternative to using RasMol.