Arunas Liuiza

This plugin enables users to easily note the source of republished text. It adds a custom post type ‘Sources’ and a metabox to choose from various sources in post editing window.
ATTENTION: This is still an early development version (aka ALPHA), thus use with your own risk. It has the basic functionality, but not many configuration options and some bugs are probably present.
Basic functions:
<ul>
<li>Allows to create list of possible sources using Custom Post Types functionality;</li>
<li>Creates a meta-box in post editor screen to choose from list of available sources;</li>
<li>Customizable template – you can use your own html and shorttags %title%, %title_attr%, %text%, %img%, %img_h%, %img_w% and %link%;</li>
<li>You can use template tag <code><?php tinysource_show(); ?></code> to insert plugin output;</li>
</ul>
TO DO:
<ul>
<li>More customization options</li>
<li>Automatic insertion after post text</li>
<li>Localization</li>
</ul>

tinySource

This plugin enables users to easily note the source of republished text. EARLY DEVELOPMENT VERSION. DO NOT USE IN PRODUCTION ENVIRONMENT.

dflydev

This project is available for forking on GitHub:
<ul>
<li>https://github.com/dflydev/embed-github-gist</li>
</ul>
Embed <a href="http://github.com/" rel="nofollow ugc">GitHub</a> <a href="http://gist.github.com" rel="nofollow ugc">Gists</a> into 
WordPress. Provides a shortcode for posts and pages but also has the ability 
to embed by hand in the event that a Gist needs to be embedded somewhere in 
the page that does not pass through the shortcode filters.
Examples:
<pre><code>[gist id=546764]
[gist id=546764 file=file.txt]
[gist id=546764 file=file.txt bump=1]
[gist]http://gist.github.com/546764[/gist]
</code></pre>
Cache is implemented with the Transients API to minimize delay on loading 
content. Default TTL (time to live) is 86400 seconds or one day.
<h4>Upcoming features:</h4>
<ul>
<li>Option for setting default TTL</li>
<li>Option to bypass cache entirely</li>
<li>Implement admin interface to control options</li>
</ul>

tinySource vs Embed GitHub Gist