Github-wiki-print is a project mainly written in ..., it's free.
Browser extension to make GitHub wiki pages printable.
Every tried to print a GitHub wiki page? It kinda sucks since there's no printer stylesheet.
This extension solves the problem by adding one.
Download the packaged extension for your browser from http://iamamused.github.com/github-wiki-print.
Navigate to your wiki page.
Select "print" from the menu in your browser.
Enjoy!