Mark Barnes

<p>You can add CSS to the entire website, regardless of what theme is being used, or add it to just the current theme. You can even add CSS that displays only when you are logged on – very useful when you’re playing with a new look, and it’s not quite ready for public viewing.</p>
<p>That’s it! There are no other options, everything is deliberately kept simple. Everything is stored in the database, so you don’t even have to worry about file permissions on your CSS files. Even better, all three styles are served in one external CSS file which is only loaded if you have actually made any tweaks – so no wasted HTTP requests.</p>


Style Tweaker

Style Tweaker is a simple Wordpress plugin that allows you to tweak your site's CSS files to your heart's content.

Blintux

<p>With this plugin you can turn on/off some theme and core services of WordPress or even you can customize it too.</p>
<h4>Frontend features</h4>
<ul>
<li>Remove generator meta tag</li>
<li>Remove RSD (Really Simple Discovery ) link</li>
<li>Remove Windows Live Writer link</li>
<li>Remove post relational links (prev, next)</li>
<li>Remove canonical link</li>
<li>Remove RSS feed links</li>
<li>Remove admin bar</li>
<li>Remove the Website URL field from the comment form</li>
<li>Remove allowed HTML tags text from the comment form</li>
<li>Quick maintenance</li>
<li>Force login</li>
<li>Open Graph meta tag generator</li>
</ul>
<h4>Backend features</h4>
<ul>
<li>Disable core (WordPress) update notification</li>
<li>Disable plugins update notification</li>
<li>Disable themes update notification</li>
<li>Hide login error messages</li>
<li>Define custom login error message</li>
<li>Enable “All Settings” item in Settings menu</li>
<li>Enable Link Manager feature</li>
<li>Enable Featured image support</li>
<li>Enable excerpt field for pages</li>
<li>Enable TinyMCE Editor for excerpt</li>
<li>Enable categories for pages</li>
<li>Display IDs in post/page list</li>
<li>Customize WP Mail</li>
<li>Remove WordPress version from footer</li>
</ul>
<h4>System information</h4>
<ul>
<li>Server time</li>
<li>Memory usage</li>
<li>SQL Queries</li>
<li>Post revisions</li>
<li>Disc usage</li>
</ul>
<h3>Arbitrary section 1</h3>


WP Caregiver

Adds many options for tweaking frontend and backend of your WordPress site.

Style Tweaker vs WP Caregiver