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.

mayel2b

Helps you more effectively edit your themes or plugins when you only have access to a browser, by enabling syntax highlighting in WordPress’ integrated source code editors. Supports PHP, HTML, CSS and JavaScript.
Please provide any feedback at http://anetech.eu/power-code-editor/
Everything is done in JavaScript on the client side.
At this time, the following browsers are supported: 
* Firefox 1.5 or higher 
* Internet Explorer 6 or higher 
* Safari 3 or higher 
* Opera 9.52 or higher 
* Chrome
Licensed under the GNU GPL v2.
Uses the excellent CodeMirror JS library : 
http://marijn.haverbeke.nl/codemirror/

Power Code Editor

Enables syntax highlighting in the integrated source code editors. Supports PHP, HTML, CSS and JS.

tinySource vs Power Code Editor