ClassyTcl is a dynamically loadable object system for Tcl. Both a Tcl-only and a C implementation are available. It also doesn't require patches to the Tcl core, which makes installation and maintenence easier. Performance is quite adequate. The C version is gives extra speed, and makes it possible to implement some methods in C. In contrast to other object systems for Tcl, it is not modeled after the object system designed for a completely different language, such as C. The system is simple but flexible. Classes and objects are dynamic, and can easily be queried, changed, and debugged at runtime.
Clig uses a simple description file to create C-code to interprete the typical *NIX command line as well as an up-to-date usage-message and a manual page skeleton. It supports Flag, String, Int, Long, Float and Double types, with ranges, defaults, and more. The generated C-Code is ANSI but has been reported to work with C++. It is self contained code which does not depend on any library other than libc. Included is a TCL-only TCL-package to instrument your TCL scripts the same way as your C-programs.
CMUbik is a library for mantaining a syncronized Berkeley database over multiple hosts. It has good failure semantics and strong authentication provided by the Cyrus SASL library. Its API is very similar to that of Berkeley DB, allowing existing applications to use it very easily.
CMVision is a real-time color classification and segmentation library which can track up to 256 colors in a 640x480 30fps video stream. The vision system core is a C++ library which is easily extensible for custom applications, and should compile on any *nix compatible environment. Also provided is a video capture library for Video4Linux II.
Apache Cocoon is a Web development framework built around the concepts of separation of concerns and component-based Web development. Cocoon implements these concepts around the notion of "component pipelines", each component on the pipeline specializing on a particular operation. This makes it possible to use a Lego(tm)-like approach in building Web solutions, hooking together components into pipelines without any required programming.
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.
Common C++ is a highly portable C++ class library meant primarily for the development of portable threaded applications. Support is provided both for POSIX platforms and native builds under Win32. The goal is to provide a truly common C++ framework for writing portable threaded applications that do not require a huge amount of runtime overhead to support, and hence can make C++ and threads suitable even for the development of trivial servers and applications.