http://odf-converter.sourceforge.net/
DL latest snapshotOpenXML/ODF Translator Command Line Tool
The command line tool enables you to convert documents between the OpenDocument Format (ODF) and Office OpenXML (ECMA).
ODT2DOCX / DOCX2ODT
ODS2XLSX / XLSX2ODS
ODP2PPTX / PPTX2ODP
Also
Somehow related
Part of the Office Image Extraction Wizard
DIaLOGIKa doc2x (DOC to DOCX) and ppt2x (PPT to PPTX)