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...
FreeWRL is an Open Source, cross platform VRML2 and X3D compliant browser, with script, SAI and EAI support. Platforms supported: Linux and other Unix-style platforms; Mac OS/X; Windows. Support for mobile platforms (iOS, Android, QNX) is under development.