G3DViewer is a 3D file viewer for GTK+ supporting a variety of file types:
   - 3D Studio (.3ds, .prj)
   - LightWave (.lw, .lwb, .lwo)
   - Alias Wavefront (.obj)
   - Impulse TurboSilver / Imagine (.iob)
   - AutoCAD (.dxf)
   - Quake II Models (.md2)
   - Neutral File Format (.nff)
   - 3D Metafile (.3dmf, .3mf, .b3d)
   - Caligari TrueSpace Objects (.cob)
   - Quick3D Objects & Scenes (.q3o, q3s)
   - VRML 1.0 files (.wrl, .vrml) (still buggy)
   - AC3D objects (.ac, .acc)

Some of the features are:
   - Wireframe mode
   - Texture support
   - Specular lighting (not really nice at the moment)
   - changable background color :)

WWW: http://automagically.de/index.shtml?g3dviewer