The Writer2xhtml export filter
The XHTML+MathML combination is designed to bring mathematical documents to the web, so you may (should) prefer this format to make documents containing formulas available online. The export filter Writer2xhtml will convert your document with as much formatting as possible preserved. Alternatively you can use your own stylesheet to format the document. For documents without formulas, Writer2xhtml also offers to convert to HTML4 compatible XHTML.
Since a printed document is quite different from an online document, Writer2xhtml ignores certain formatting (page style, columns) and creates a lot of hyperlinks, eg. for cross references, to/from footnotes, from the alphabetical index etc. You can use this to publish Writer documents to the web, or you can use it to produce rich content for a Content Management System.
The EPUB format is an open standard for e-books based on XHTML 1.1. It is designed to provide reflowable content for optimal representaion on the reading device. Writer2xhtml provides an easy way to publish your document in EPUB format.
Writer2xhtml will aim to produce valid XHTML documents that are a faithful representaion of the original document, while adapting it to an online context.