Things that have not be put elsewhere.
[http://lists.debian.org/debian-science/2005/08/msg00002.html For logging into the compute cluster on the other coast I use VNC running down an SSH tunnel. This is much faster than using SSH's X11 forwarding capability. ]
Program which can be used non-interactively to be used in web applications or something else
[http://lists.debian.org/debian-science/2005/08/msg00052.html For non-interactive applications (e.g. web) one can use R. Note that R's PNG and JPEG devices rely on having an X server present. I've had success with R producing EPS output, and then using Imagemagick's convert command, which calls Ghostscript behind the scenes, to rasterize it.]
See also [http://lists.debian.org/debian-science/2005/08/msg00071.html this]
Similarly to the above, some functionalities of yorick (e.g. writing a mpeg movie using yorick-mpeg) require the openning of an X window. When I want to do it non-interactively, I use a VNC server instead of a "real" X11 display. Other "dummy" X11 servers suitable for this sort of tricks may exist. ThibautPaumard.