Cool Stuff

Here I list a few pieces of software I use and like, in no particular order.  They can all be obtained free of charge.  (There are also commercial versions of SSH and TeX.)  The small images on the left link to sites with more information.  Operating systems the software runs on are listed in the right column.

Software from the GNU Project is pervasive on Linux systems and essential to their operation.  I omit GNU programs (except for the GIMP and GCC) from the list below; consider this an overall recommendation.

Note 1: For brevity, mention of Unix as a operating system implies tacit mention of Linux, BSD derivatives, etc., even though they are not registered UNIX® systems.  This includes Mac OS X.  Also for brevity, mention of Mac or MacOS below refers to the older, non-Unix Mac operating systems.

Note 2: X is the X Window System, Version 11, which runs under several operating systems, including Windows and MacOS.  The combination of an operating system and X will be indicated as in "VMS/X".

Note 3: Cygwin provides a Unix environment under Windows. A Windows system with Cygwin will be indicated by "Windows/Cygwin".
SoftwareDescriptionSystems
[TeX]
and
[LaTeX]

TeX creates high-quality typeset documents from files written with any plain-text editor. If you write equations and want them to look good, you need TeX, but it's great for nontechnical stuff too, as this book sampler illustrates.  A variety of examples, both technical and nontechnical, appear in the TeX Showcase.

LaTeX is a widely-used TeX macro package, whose fancier capabilities are amply illustrated in Peter Flynn's promotional leaflet (PDF, 817 KB).  For simple, everyday work LaTeX is easy to use: for a very small example see the plain text LaTeX source for this PDF file (9 KB). (New Yorkers, it's just a joke.)

See also the Jargon File entry for TeX.

 Unix, Windows, Mac, VMS, OS/2, MS-DOS, Amiga, Atari, . . .
[Mutt] Mail User Agent, for reading and composing mail. Fast, versatile, and highly configurable. Unix, Windows/Cygwin
[Fetchmail] Mail retriever. It supports POP2, POP3, RPOP, APOP, KPOP, IMAP, ETRN, and ODMR, and can use SSH port-forwarding or SSL for encrypted retrieval. Unix, Windows/Cygwin, BeOS, Amiga
[SSH] Software (see Table of SSH Implementations) implementing the SSH protocols provides encrypted communications between two computers over insecure networks, and allows the user to work on remote machines, transfer files, retrieve e-mail, etc., securely. Unix, Windows, Mac, VMS, BeOS, PalmOS, MS-DOS, . . .
[Ghostscript] Ghostscript is a PostScript and PDF interpreter. It converts PostScript and PDF to a variety of printer and display formats, and can create PDF from PostScript. Unix, Windows, Mac, VMS, OS/2
[gv] gv (a GUI front-end to Ghostscript) is a PostScript and PDF viewer. Unix/X, VMS/X
[xv] xv is an image viewer that can also do some image processing. It is shareware, but the author's terms are very liberal; he had no problem when TV coverage at the Jet Propulsion Laboratory of NASA's Mars Pathfinder Mission caught an unregistered copy in use. Unix/X, VMS/X, WinNT/X, BeOS/X
[The GIMP] The GIMP is a Photoshop-like image processor. Unix/X, Windows
[GCC] The GNU Compiler Collection has a common back end and front ends for C, C++, Objective C, Fortran, Ada, and Java.  I would be unable to do my work without compilers.  The GCC compilers are excellent and popular freeware. Unix, Windows/Cygwin, MS-DOS