Many programs nowadays can produce ePUB publications from document sources, which includes Microsoft Word formats (.doc, .docx). This includes many word processors, document layout programs, ebook management tools or even some dedicated digital book converters, all of them should be capable of doc to epub conversion or export just fine.
Open DOC file Open EPUB fileA shareware word processor program
A program for ePUB conversions
A text to epub converter
A personal information manager