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.
U++ is a C++ cross-platform rapid application development suite focused on programmers' productivity without sacrificing runtime performance. Based on strictly deterministic design, it provides a viable alternative to garbage-collected platforms, even for business logic oriented problems.
Steel Bank Common Lisp is a development environment for Common Lisp, with excellent support for the ANSI standard: garbage collection, lexical closures, powerful macros, strong dynamic typing, incremental compilation, and the famous Common Lisp Object System (multimethods and all). It also includes many extensions, such as native threads, socket support, a statistical profiler, programmable streams, and more. These are all available through an integrated, interactive native compiler which feels like an interpreter. SBCL is unique in being a multiplatform native compiler which bootstraps itself completely from source, using a C compiler and any other ANSI Common Lisp implementation.
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.
crypt_blowfish is an efficient implementation of a modern password hashing algorithm, based on the Blowfish block cipher, provided via the crypt(3) and a reentrant interface. It is compatible with bcrypt as used in OpenBSD. It is adaptable to future processor performance improvements, allowing you to arbitrarily increase the processing cost of checking a password while still maintaining compatibility with your older password hashes. The hashes it produces are several orders of magnitude stronger than traditional Unix DES-based or FreeBSD-style MD5-based hashes.
libjio is a C library to do journaled, transaction-oriented I/O. It provides a UNIX-like set of file operation functions (such as open, read, and write), which are wrapped in a transaction framework, so that file operations can be committed or rolled back as necessary. It is non-intrusive, atomic, and thread-safe, with fast crash recovery.
Releaser is a set of scripts to automate and manage the tasks related to software package releases. It is designed to be modular and to make it easy to both select a particular set of actions associated with releases of a particular project (such as changelog generation, uploading of tarballs, posting announcements to mailing lists), and create new actions that integrate seamlessly into the process. Its status is still somewhat experimental, but the most basic functionality is there.