robertferanec

This plugin backups the content which you write on the Edit page. It will upload it to GitHub or it will download it from GitHub.
When you are writing a page/post and you would like to backup the text, you can use this plugin. If anything happen to your server, you always will have the texts on GitHub.
This plugin can also be used for collaboration. You can easily see and track any changes done by other people + you can comment the changes on GitHub.
With this plugin you can easily synchronize content of WordPress posts or pages between mutliple servers. For example, you (or someone else) can create/update posts and pages on your test server, then you can check the changes on Github and once you are happy with them, just go to your live server, press a button to download the the changes from GitHub and publish them on your live website.

Posts and Pages GitHub Backup

Backups WordPress content of your posts and pages to GitHub

Claudio Sanches

This plugin adds Github Gists in your posts via shortcode.
Examples
Add a full gist:
<pre><code>[gist id="3837669"]
</code></pre>
Add a specific file in a gist:
<pre><code>[gist id="3837669" file="index.php"]
</code></pre>
<h3>License</h3>
Gist GitHub Shortcode is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published 
by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
Gist GitHub Shortcode is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of 
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with Gist GitHub Shortcode. If not, see <a href="http://www.gnu.org/licenses/" rel="nofollow ugc">http://www.gnu.org/licenses/</a>.

Gist GitHub Shortcode

Adds Github Gists in your posts via shortcode

Posts and Pages GitHub Backup vs Gist GitHub Shortcode