1. LibnoiseA portable, open-source, coherent noise-generating library for C++
2. Box2dBox2D is an open source C++ engine for simulating rigid bodies in 2D. Box2D is developed by Erin Catto and has the zlib license.
3. ExamplesSmaller or bigger examples that I've written or will write in the future in C++.
4. PubBusA simple implementation of a MessageBus.