PLplot is a cross-platform, scientific graphics plotting library that supports math symbols and human languages (via UTF-8 user input strings); plot capabilities for multiple non-interactive plot file formats and in multiple interactive environments; and bindings for multiple computer languages.
PyMOL is an OpenGL based molecular visualization system
The Open-Source PyMOL repository has been moved to github:
https://github.com/schrodinger/pymol-open-source
We still use the pymol-users mailing list here on sourceforge. Please subscribe for community support: https://pymol.org/maillist (Note: SourceForge email newsletter and special offers are optional and can be unchecked)
The PyMOL community wiki has its own home:
https://pymolwiki.org/
ProcessViewBrowser & ProcessViewServer represent an OpenSource attempt to industrial process visualization. It is based on Qt and is very portable. (Now also available as commercial software)
The 3D Slicer is freely available, open-source software for visualization, registration, segmentation, and quantification of medical image data. Follow the link for more info: http://slicer.org