Simple SMD to OBJ python script that uses blender python API. You will need to have blender source tools addon installed for blender to import smd files. http://steamreview.org/BlenderSourceTools/
Can be used to import other file formats and export them into various file formats depending if an addon or blender supports it.
Generally, bpy.ops.export_scene.<format> and bpy.ops.import_scene.<format> is to be edited.