Sergey Biryukov

WordPress Multisite (3.0+) already comes with theme and plugin editor enabled by default. This plugin is available for reference only.
Allows to enable theme and plugin editor for site administrator in WordPress MU. 
Requires Site Admin capabilities, not just blog administrator.
Based on the <a href="http://www.clickonf5.org/wordpress-mu/enable-theme-plugin-editor-wordpress-mu/5790" rel="nofollow ugc">non-plugin solution</a> by Sanjeev Mishra.

Enable Theme and Plugin Editor (WPMU)

Allows to enable theme and plugin editor for site administrator in WordPress MU.

Thomas Lloancy

Simple Editor Control silently records every file change made through the WordPress built-in plugin editor and theme editor. For each save it stores the diff, the editor who made it, and the timestamp — giving you a full, browsable history.
Features
<ul>
<li>Automatic tracking — no setup required. Every save through the WP file editor is captured.</li>
<li>Git-style diff viewer with side-by-side and line-by-line modes.</li>
<li>Adjustable context lines (0, 3, 5, 10, 20).</li>
<li>Point-in-time file recovery — download any file as it existed at any past revision.</li>
<li>Works with all plugins and all active themes.</li>
<li>Accurate LCS-based diff engine (same algorithm as GNU diff / git) — handles insertions, deletions and replacements correctly.</li>
<li>Fully translatable.</li>
</ul>
Use cases
<ul>
<li>See exactly what changed when something broke.</li>
<li>Verify that no unauthorised changes were made to your plugin or theme files.</li>
<li>Recover a previous version of a file without restoring a full backup.</li>
</ul>

Simple Editor Control


Wordpress editor is very handy, and you can see the difference made when a plugin or theme was edited using that tool. It's my plugin and i like it


Go and download it

Audit trail and git-style diff viewer for every file change made through the WordPress plugin and theme file editor.

Enable Theme and Plugin Editor (WPMU) vs Simple Editor Control