Grace is a WYSIWYG 2D plotting tool for the X Window System and M*tif.
Jmol is a viewer for chemical structure data.
Lynx is a text based web browser.
Maestro is a graphic interface for Jaguar.
OpenCV is an open source computer vision library.
Ploticus is a free GPL software utility that can produce various types of plots and graphs.
PyMOL is an OpenGL based molecular visualization system
VMD is a molecular visualization program for displaying, animating, and analyzing large biomolecular systems using 3-D graphics and built-in scripting.