A readable lisp in less than 1k lines of C
PHIGS (Programmer's Hierarchical Interactive Graphics System)
GNU Telephony Services and Applications
An open source interactive disassembler
scientific programming language and graphics
Graph algorithms interpreter, IDE, debugger, 3D visualizations.
Light-weight C++ web application server library
Kinect based controller.
A C++ plugin library
Boost.Application
A lightweight, high-level, and object-oriented scripting language.