Extension:Gists

The Gists extension allows you to embed Github's gists using the  tag.

Usage
The following Gist:

https://gist.github.com/foxfirefey/4964230

Uses this to embed:

4964230

And shows up as such:

View code at: https://gist.github.com/4964230.js

file argument
Use this to embed a specific file:

9263794

View code at: https://gist.github.com/9263794.js?file=nginx.conf