2ePub is a free online converter that allows you to convert various types of documents and e-books (such as pdf, doc or fb2, etc.) to ePub format, the standard file format for e-books that is supported by almost every e-book reading device including iPad, Sony Reader, BeBook, IREX Reader, iPhone, Nook, etc.
ePub makes books more accessible on phones, netbooks and e-ink readers allowing reader software to reflow the text in order to accommodate different font sizes, layouts and screens of devices.
2EPUB converter supports the following formats:

• input: doc, epub, fb2, html, lit, lrf, mobi, odt, pdb, pdf, prc, rtf, txt.
  
• output: epub, fb2, lit, lrf, mobi.