rtfx converts RTF files into a generic XML format. It focuses on keeping metadata such as style names rather than every bit of formatting. This makes it handy for converting RTF documents into a custom XML format (using XSL or an additional processing step). It used to be called 'rtfm', but was changed due to a naming conflict.
RetroWeb is an extension for RetroForth intended to ease the task of creating Web pages. It is still close to HTML, but offers a more compact syntax. Most importantly, it allows you to work with the full power of Forth to generate HTML code. It can be used to create both static HTML files and simple dynamic CGI responses.
lxml is a Python binding for the libxml2 and libxslt XML processing libraries. It aims at ease of use of the API for Python programmers and exposing the many libxml2 features. It implements the Python ElementTree API on top of libxml2. It extends this with support for XPath, XSLT, Relax NG, XML schema, and more.