Ghostscript is a processor for PostScript and PDF files. It can rasterize these files to a wide variety of printers, devices for screen preview, and image file formats. Since applications tend to prepare pages for printing in a high-level format such as PostScript, most Unix users with low-level bitmap printers, such as inkjets, use GhostScript as part of the printing process. In addition, Ghostscript is capable of converting PostScript files, functionality comparable to Adobe Acrobat Distiller, but on the command line. In addition, Ghostscript is used for file import and viewing by a great many other applications, including xv, ImageMagick, gimp, and xdvi. Several GUI wrappers for viewing PostScript and PDF files exist, including GSview, ghostview, gv, ggv, and kghostview. This is far from a comprehensive list.
album is a free HTML/XHTML photo album and gallery generator that supports themes/skins. You can choose different themes or write your own to get different layouts and styles. It creates all your thumbnails (including directory thumbnails) and descends into directories so you can organize your photos. See the home page for more examples. album is also multi-lingual, with many languages being added all the time. N.B.: The purchase link is provided for donations; the software does not cost anything.
Xpdf is a viewer for Portable Document Format (PDF) files. (These are also sometimes also called 'Acrobat' files, from the name of Adobe's PDF software.) The Xpdf project also includes a PDF text extractor, PDF-to-PostScript converter, and various other utilities. It runs under the X Window System on UNIX, VMS, and OS/2. The non-X components (pdftops, pdftotext, etc.) also run on Win32 systems, and should run on pretty much any system with a decent C++ compiler. Xpdf is designed to be small and efficient. It can use Type 1 and TrueType fonts.
white_dune is a graphical VRML97/X3DV editor, simple NURBS/Superformula 3D modeller, animation tool, and VRML97/X3DV commandline compiler in development. VRML97 (Virtual Reality Modeling Language) is the ISO standard for displaying 3D data over the Web via browser plugins ("HTML for realtime 3D"). X3DV is the direct successor of VRML97. VRML97 and X3DV have support for animation, real-time interaction, and multimedia (images, movies, and sounds). white_dune can read, create, and display VRML97/X3DV files and let the user change the scenegraph/fields. It also has support for stereoscopic view via "quadbuffer"-capable stereo visuals, and support for 3D input devices like a joystick, spaceball, or magnetic tracker.
RoadMap is a navigation program for Unix and PocketPC that displays street maps. Most of the maps are provided by the US Census Bureau, and thus only the US has a decent coverage at this time. A specific area can be displayed by entering a street address (street number, street name, city, and state). It interfaces with a GPS receiver through gpsd or the serial line to track the car position. It has been designed to be usable on a Linux desktop or laptop computer, or on a PDA (Linux or PocketPC).
BEYE (Binary EYE) is a portable advanced file viewer with a built-in editor for binary, hexadecimal, and disassembler modes. It contains a highlighting Java/AVR/i86-AMD64/ARM-XScale/PPC64 disassembler, full preview of MZ, NE, PE, LE, LX, DOS.SYS, NLM, ELF, a.out, arch, coff32, PharLap, and rdoff executable formats, a code guider, and many other features.
OpenVRML is a VRML and X3D browser plug-in and C++ toolkit for incorporating VRML/X3D support into applications. It provides VRML97 and Classic VRML X3D parsers, a runtime, and an OpenGL renderer as C++ libraries. The renderer is fully separate from the runtime library so that users can also provide their own renderer. The OpenVRML browser is provided as a D-Bus service, and is embeddable in host applications using XEmbed. The distribution provides both a stand-alone host and a host that runs as a Mozilla plug-in.
Coin is an implementation of Open Inventor. Open Inventor is the de facto standard API for retained-mode 3D graphics programming. Open Inventor has a highly extensible design, and has been designed to allow for rapid development of highly interactive 3D graphics applications in the fields of CAD, engineering, scientific computing, simulation, VRML, and visualization.