BRL-CAD is a powerful constructive solid geometry solid modeling system that includes an interactive geometry editor, ray-tracing support for rendering and geometric analysis, path-tracing for realistic image synthesis, network distributed framebuffer support, and image and signal-processing tools.
Java Development Environment for Emacs (JDEE) is an Emacs-based integrated development environment (IDE) for developing Java applications and applets. Features include multiple code browsers, a JPDA-based debugger, method and field completion, template-based and procedure-based code generation, Java source code interpreter, context-sensitive help, and more.
ICI is a general purpose interpretive programming language that has dynamic typing and flexible data types with the flow control constructs and operators of C. It is designed for use in many environments, including embedded systems, as an adjunct to other programs, as a text-based interface to compiled libraries, and as a cross-platform scripting language with good string-handling capabilities.
Jhead is a command line driven utility for extracting digital camera settings from the Exif format files used by many digital cameras. It handles the various confusing ways these can be expressed, and displays them as F-stop, shutter speed, etc. It is also able to reduce the size of digital camera JPEGs without loss of information, by deleting integral thumbnails that digital cameras put into the Exif header. If you need to add Exif support to a program, this is a simple program to cut and paste from. Many projects, including PHP, have reused code from this utility.
The Simple Sockets Library makes sockets easy to use and comes as public domain source code. It resembles C's file I/O, uses whatever port is available, has named servers and port reuse, streaming/blocking sockets used, polling support, blocking/selection support via numerous functions, timeout control and firewall support.
TEA Total is a collection of extremely small encryption tools. At the heart of TEA Total is the TEA (Tiny Encryption Algorithm): a fast and secure 128-bit private key algorithm which was developed and placed in the public domain by David Wheeler and Roger Needham of the Cambridge Computer Laboratory.