Stereofy is a command line program to produce anaglyph images. Take a look at Wikipedia to see what I am talking about.
You can get the software from svn:
svn co http://svn.plutz.net/stereofy/trunk sterofy
A manual as well as installation instructions can be found in the wiki section.
you can now alter the display parallax of your stereo image by using the
As of commit revision 6 this program is Free Software.