Weasyprint is an excellent tool for converting HTML to PDF. It has supported CSS Paged Media Module for a while; this has been very useful for making printable PDFs from web pages.

Weasyprint seems to be one of the few HTML->PDF engines out there that doesn't depend on a browser engine. It's impressive just how much works (HTML, CSS, SVG, etc), given that this is a relatively simple project compared to a full-featured browser. Performance isn't bad, considering it is implemented in Python.