annoyme is a program that plays a sound effect every time you hit a key on your keyboard to give you the feeling you are using a real typewriter. This can be used to impress colleagues with your typing skills or just for sentimental reasons. It supports various sound input methods, as well as multiple output libraries like ALSA or AO. Most importantly, it is also possible to add more sound themes. Currently, only input for XEvIE (on an X Server) is supported.
Quad-Ren is a resolution independent 2D graphics engine that aims to ease the development of bitmap-based applications, primarily games. It will run regardless of screen resolution or aspect ratio, and works flawlessly with tiling window managers. It rectifies many of the issues with older methods of 2D game development such as color key transparency (which inevitably leads to aliasing) and having to draw sprites in a specific order, which Quad-Ren handles using alpha transparency and layers respectfully. It is programmed in, and usable from C++, with a simple object-oriented API and a small, well documented, easy to edit code base.
Visualization Library is C++ middleware for high-performance 2D and 3D graphics applications based on the industry standard OpenGL 1.x-4.x, designed to develop portable applications for the Windows, Linux and Mac OS X operating systems. It supports advanced features like OpenGL Shading Language, Volume Rendering, Isosurface extraction, Frame Buffer Objects, Multiple Render Targets, Vertex and Pixel Buffer Objects, KdTree/AABB frustum culling, a multilingual Unicode-based text engine, advanced texturing, DDS cubemaps, mipmaps, compressed textures, and much more. Visualization Library can be especially useful in 3D/2D scientific visualization, virtual reality, augmented reality, visual simulation, data visualization, presentations, multimedia applications, special effects, and 3D/2D games.