There is a library for “asset import” with a BSD-style license that has a Github repository at https://github.com/assimp (there is a fork of the repository on the ReliaSolve site at https://github.com/ReliaSolve/assimp where we put bug fixes and improvements prior to sending pull requests).
The library builds using CMake. The Release version builds out of the box on Windows (there is a linking problem with the latest RelWithDebInfo). There is an OpenGL viewer program that compiles with ASSIMP_BUILD_SAMPLES turned on. It runs on the Mac, Linux and Windows if you have Glut.
We’re using this in the Visual Common Ground project.