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.
Fl_Editor is a word-wrapping text editor widget for the FLTK toolkit. It supports CUA-style editing keys, automatic scrollbar display, load and save to file or buffer, and more. Fl_Editor includes subclasses with status and position display, find and replace, a couple of utility widgets, a status panel and a progress bar that can be used independent of any of the editors.
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.
Freemed-YiRC is a PHP package based on Freemed for use with Youth in Residential Care (YiRC) agencies. Its aim is to be a complete package to replace legacy non-free apps which aren't customizable. Since it's PHP-based, all that is needed for the client is a good Web browser with extensive table support. Some of the objectives for Freemed-YiRC are: User Management, a Contact Database, Clinical CaseNotes, an Incident Report System, an email client, a Service Plan System, a Timecard System, and Medical Billing (Medicaid/Insurance/Private).
Frodo is a free, portable C64 emulator. It focuses on the exact reproduction of graphical effects possible on the C64, and comes in three "flavors" (Frodo, Frodo PC, and Frodo SC) with increasingly higher quality of emulation, but at the cost of higher processing power requirements. Frodo has been ported to a number of systems, including handheld computers. The Unix version can use either SDL, X11, or SVGAlib to display the graphics.
Fugu is a standalone, graphical client for the Gale instant messaging system. It is fully featured and supports all common Gale messaging operations. In addition, Fugu features a Windows port, multiple screens for different subscription lists, clickable URLs, thumbnail pictures showing the sender of each message, and configurable notification when new puffs arrive.
FXPy is a Python extension module which provides an interface to the FOX cross-platform GUI library. With a few minor exceptions, FXPy provides a complete interface to FOX. FOX is a C++-based toolkit for developing graphical user interfaces easily and effectively, and it runs natively under both Unix/X and Microsoft Windows. Some of the significant features of FOX include a rich set of widgets, powerful but easy-to-use layout managers, extensive support for 3-D modeling using OpenGL or Mesa, drag-and-drop (using the XDND protocol) and a registry for persistent application settings.