An EFI boot manager utility
rEFInd is a fork of the rEFIt boot manager. Like rEFIt, rEFInd can auto-detect your installed EFI boot loaders and it presents a pretty GUI menu of boot options. rEFInd goes beyond rEFIt in that rEFInd better handles systems with many boot loaders, gives better control over the boot loader search process, and provides the ability for users to define their own boot loader entries.
Open Source Solid Modeling CAD
BRL-CAD is a powerful cross-platform constructive solid geometry solid modeling system that includes an interactive geometry editor, ray-tracing for rendering & geometric analyses, network distributed framebuffer support, image & signal-processing tools.
An open-source Phantasy Star Online server for *nix
Sylverant is an open-source server for the Phantasy Star Online series of games by Sega, written primarily for Unix-like operating systems. Sylverant has at least partial support for most versions of Phantasy Star Online, from the Network Trial for the Dreamcast through Blue Burst for Windows.
A fast, unobtrusive and modern cross-platform GUI toolkit. Agar fully exploits hardware acceleration where available, but also supports simple frame-buffer interfaces. Agar is stand-alone and easily portable to new platforms and graphics systems.
The Alhacen Ray Tracer is an open source real time ray tracer aimed at achieving competitive 3d graphics performance on everyday computers while allowing for dynamic reflections and global illumination. It is written in the C programming language.
The Objective-C Interactive Simulation Abstraction Layer
SimKit(because GameKit was taken) is designed to allow quick and easy cross platform abstraction away from platform dependant drawing and physics libraries. The APIs provide a generic way to make common calls for drawing, animating, and otherwise manipulating 3D entities, as well as shading and texture information.