WeasyPrint converts web documents to PDF.
WeasyPrint is a visual rendering engine for HTML and CSS that can export to PDF. It aims to support web standards for printing. WeasyPrint is free software released under the BSD license.
It is based on various libraries for parsing, text and drawing but not on full a rendering engines like WebKit on Gecko. The CSS visual rendering is written in Python and meant to be easy to hack on.
See the website and documentation at http://weasyprint.org/