The Open Asset Import Library (short name: Assimp) is a portable Open-Source library to import various well-known 3D model formats in a uniform manner. The most recent version also knows how to export 3d files and is therefore suitable as a general-purpose 3D model converter. See the feature-list. open3mod is a Windows-based model viewer. It loads all file formats that Assimp supports and is perfectly suited to quickly inspect 3d assets. Assimp aims to provide a full asset conversion...
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.
Openmark will be a Open Source benchmark that will have 32/64 bit options for video rendering tests on X11 as well as HD speed, FSB, etc benchmarks. Also many tools like: temp monitor, speed control, etc.