CINEMA 4D is a 3D modeling, animation, motion graphic and rendering application developed by MAXON Computer GmbH in Germany. It is capable of procedural and polygonal/subd modeling, animating, lighting, texturing, rendering, and common features found in 3D modelling applications.
Cinema 4D Plugin for importing, exporting, and manipulating filetypes created by Valve Corporation's Source Engine. VTF Import/Export, SMD/QC Importer (ongoing development).
This Game-Oriented DCC Tools plug-in Imports and Exports .smd files (both mesh reference and skeletal animation types) as well as Ogre3D (.mesh and .skeleton) files and MilkShape3D binary .ms3d files, allowing you to easily convert between those formats and/or develop in those formats directly in Cinema 4D. Note that this is not a "free" plug-in, but is priced with hobbiests in mind.