3Delight is a very fast RenderMan-compliant renderer designed to produce photorealistic images for serious production environments. Some of its features include ray tracing, global illumination, motion blur, depth of field, subdivision surfaces, programmable shaders, quality antialiasing, and antialiased multi-depth shadow maps. The API and the shading language are very similar to what is described in the RenderMan interface documentation.
64 Studio is a collection of native free software for digital content creation on x86_64 hardware (AMD's 64-bit CPUs and Intel's EM64T chips). It's based on the pure 64 port of Debian GNU/Linux, but with a specialised package selection and lots of other customisations. The distribution includes the Linux kernel with realtime preemption patches, the GNOME desktop, and a selection of creative applications, covering audio and music, 2D and 3D graphics, and publishing for the Web and print. It also includes Internet and office tools that a creative user is likely to need for their daily work.
AA-lib is a low level gfx library just as many other libraries are. The main difference is that AA-lib does not require graphics device. In fact, there is no graphical output possible. AA-lib replaces those old-fashioned output methods with a powerful ASCII art renderer. The API is designed to be similar to other graphics libraries.
ACFTools is a utility for manipulating X-Plane flight simulator aircraft and weapon models without using its Plane Maker. It can decode both Apple and Intel ACF/WPN formats into plain text files with a syntax similar to C, which can be edited and then re-converted into binary data. It is able to extract almost complete 3D models of aircraft (fuselage, floats, tanks, wings, stabs, propellers, engines) and write it in AC3D modeler format. Edited 3D parts can then be merged into plain text and consequently converted into binary ACF files.