Ettercap is a network sniffer/interceptor/logger for ethernet LANs. It supports active and passive dissection of many protocols (even ciphered ones, like SSH and HTTPS). Data injection in an established connection and filtering on the fly is also possible, keeping the connection synchronized. Many sniffing modes were implemented to give you a powerful and complete sniffing suite. Plugins are supported. It has the ability to check whether you are in a switched LAN or not, and to use OS fingerprints (active or passive) to let you know the geometry of the LAN.
Euphoria is a simple, flexible, easy-to-learn programming language. It lets you quickly and easily develop programs for Windows, Linux, FreeBSD, NetbSD, OpenBSD, and Mac OS X. Although Euphoria provides subscript checking, uninitialized variable checking, and numerous other run-time checks, it is extremely fast and has the ability to compile to transparently compile native executables via C code.
f/Calc is a utility to calculate lens formulae for photographers so you can focus on the artistic bits rather than on the mathematics behind it all. f/Calc can do "f" number arithmetic, and can calculate depth of field, hyperfocal distance, the field of view of a lens, the angle of view of a lens, magnification, and how the focal length of the lens on the camera changes the way the spot metering function works. In addition to the Unix/Linux Tcl/Tk version, there are native Windows, Palm OS, and Macintosh versions as well.
The Faq-O-Matic is a CGI-based system that automates the process of maintaining a FAQ (or Frequently Asked Questions list). It allows visitors to your FAQ to take part in keeping it up-to-date. A permission system also makes it useful as a help-desk application, bug-tracking database, or documentation system.
The Fink project wants to bring the full world of Unix Open Source software to Darwin and Mac OS X. It modifies Unix software so that it compiles and runs on Mac OS X and makes it available for download as a coherent distribution. Fink uses Debian tools like dpkg and apt-get to provide powerful binary package management. You can choose whether you want to download precompiled binary packages or build everything from source.
fli4l is a single-floppy Linux-based ISDN/DSL/ethernet-router. It features configuration with some simple ASCII-files, several possible connection-flavors (in/out/callback, and raw IP/PPP), channel bundling (an extra channel can be added through a Windows/Unix-client), configuration of multiple networks, least-cost routing, automatic choice of provider, display/calculation of connection times and costs, and a Windows/Unix client to control dial/hangup, monitor traffic and monitor incoming calls on ISDN (see screenshot).
FLTK (pronounced "fulltick") is a cross-platform C++ GUI toolkit for UNIX/Linux (X11), Microsoft Windows, and Mac OS X. It provides modern GUI functionality without the bloat, and supports 3D graphics via OpenGL and its built-in GLUT emulation. FLTK is designed to be small and modular enough to be statically linked, and also works fine as a shared library. It also includes an excellent UI builder called FLUID that can be used to create applications in minutes.
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.