From Richard Byrne Free Technology for Teachers: 2EPUB - A Free Doc to ePub Converter:
2EPUB provides a simple way to convert your text documents into ePub documents for viewing on ereaders. 2EPUB supports the conversion of many file types including Doc, Docx, ODT, PDF, and HTML. To convert your file into an ePub file simply upload your file, set the display parameters, and click convert. When the conversion is complete you can download your file and use it on any device that supports ePub display.