Atlantis Word Processor (previously known as Atlantis Ocean Mind) can be used to convert any TXT, RTF, DOC, or DOCX document to an eBook in the ePub format. Converting an existing document to an eBook in Atlantis Word Processor normally takes less than a minute. But new eBooks can be also created in Atlantis Word Processor from scratch.

http://wiki.mobileread.com/wiki/Atlantis_Word_Processor