Built-in native .NET importers for:
3DS   (Legacy 3D Studio Files)
OBJ   (Wavefront files)

Work in progress:

MS3D (Milkshape 3D)
ASE  (3D Studio MAX/Maya export format)

Importers have the option to generate normals if no normals are present, and apply smoothing groups to the normals.
Work is in progress on native ISE 3.0 geometry formats for improvements in loading speed.