Chemtool is a GTK+ based 2D chemical structure editor for X11. It supports many bond styles, most forms of text needed for chemical typesetting and splines/arcs/curved arrows.

Drawings can be exported to MOL and PDB format, SVG or XFig format for further annotation, as a PiCTeX drawing, as a bitmap or as Postscript files (several of these through XFig's companion program transfig).


Celestia is a free 3D astronomy program. Based on the Hipparcos Catalogue, it allows users to display objects ranging in scale from artificial satellites to entire galaxies in three dimensions using OpenGL. Unlike most planetarium software, the user is free to travel about the Universe.