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.
Freeciv is a multiuser reimplementation for Unix/X of the famous Microprose game of Civilization. By default, the game is an improved Civ II, but this can be customized; modpacks for near-100% compatibility with Civ I and Civ II are included. Multiuser gameplay is real-time: in each turn, all human players move concurrently. The game is designed to remain fairly playable even on poor network connections. Freeciv can also be played on standalone machines, and its AI players are a good challenge for beginners. The source code comes with the server, two X clients, and non-X clients for MS Windows and Amiga. Freeciv is released under the GNU General Public License. It is maintained by an international team of coders and enthusiasts, and is easily one of the most fun and addictive network games out there.
NASM is an 80x86 assembler designed for portability and modularity. It supports a range of object file formats including Linux a.out and ELF, COFF, Microsoft 16-bit OBJ, Win32/64, and Apple Mach-O. It will also output plain binary files. Its syntax is designed to be simple and easy to understand, similar to Intel's but less complex. It supports all currently known opcodes, and has advanced macro capability. It includes a disassembler as well.
getmail is intended as a simple, secure, and reliable replacement for fetchmail. It retrieves email (either all messages, or only unread messages) from one or more POP3, SPDS, or IMAP4 servers (with or without SSL) for one or more email accounts, and reliably delivers into qmail-style Maildirs, mboxrd files, or through external MDAs (command deliveries) specified on a per-account basis. getmail also has excellent support for domain (multidrop) mailboxes, including delivering messages to different users or destinations based on the envelope recipient address.
The ATLAS (Automatically Tuned Linear Algebra Software) project is an ongoing research effort focusing on applying empirical techniques in order to provide portable performance. It provides C and Fortran77 interfaces to a portably efficient BLAS implementation, as well as a few routines from LAPACK.
JExpress is a Java installer builder and auto-updater. It gives you your choice of a standalone installer, including both native and cross platform installers and updaters for Windows, Mac OS X, Linux, and Solaris, or a Java Web Start one-click install. You create your installer quickly with your choice of a simple wizard or a powerful advanced interface, both included. You can bundle the exact JVM you want with your installer. The auto-updater gives you a continuous revenue stream after the sale. Your software is always up-to-date, so your customers have fewer problems. You also get all the features you expect in a top end installer. Your Java application becomes a native program just like any other. On Windows it's an EXE, on Mac OS X an app bundle, etc. If you need something really special, you can customize your installer by adding simple Java classes. You can even get a source license at a reasonable price.
BORG is a calendar and task tracking system written entirely in Java. The calendar is an appointment organizer that provides a nice month view, month printing, email reminders, popup reminders, and a to do list. The task tracker tracks issues and tasks through various user-defined states.