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-formats list.
Assimp U++ package includes it in a simple manner to be used easily in U++ projects.
The best example to use it and the reason to be created is the UltimateOpenGL.3D library created by Xemuth (Clément Hamon)