Jan Štětina

Includes custom HTML/CSS/JS code in the section on every blog in the network.
Very simple, but sometimes useful plugin.
After activation visit Network Admin –> Settings –> Multisite wp_head Code for setup. Nothing else is needed.
Developed for private use, but has perspective for more extensive usage. I can’t guarantee any support in the future nor further development, but it is to be expected. Kindly inform me about bugs, if you find any, or propose new features: <a href="mailto:zaantar@zaantar.eu?subject=[multisite-wphead-code]" rel="nofollow ugc">zaantar@zaantar.eu</a>.

Multisite wp_head Code

Includes custom HTML/CSS/JS code in the  section on every blog in the network.

satourne

Head Meta Date (formerly “Head Metadate”) improves the definition and semantic quality of your web pages by adding a set of date <code><meta></code> tags to the <code><head></code> section of your web pages.
Example
<pre><code><head>
 ...

 <meta http-equiv="Date" content="Wed, 16 Feb 2011 22:34:13 GMT">
 <meta http-equiv="Last-Modified" content="Wed, 17 Feb 2011 12:34:13 GMT">
 <meta name="CreateDate" content="Wed, 16 Feb 2011 22:34:13 GMT">
 <meta name="Last-Update" content="Wed, 17 Feb 2011 12:34:13 GMT">
 ...
</head>
</code></pre>
Features
<ul>
<li>Plug-n-play functionality</li>
<li>Easy to configure from the WP Admin</li>
<li>Adds set of meta tags to <code><head></code> section of posts and pages</li>
<li>Customize each <code><meta></code> tag with your selected date info</li>
<li>Leaving any field blank generate a now date</li>
<li>Auto-generates known information from your site</li>
<li>Choose HTML or XHTML format for meta tags</li>
<li>Enable/disable plugin output from the settings page</li>
<li>Includes live preview of your meta tags and custom content</li>
<li>Option to reset default settings</li>
</ul>
This plugin is designed to complete a site’s head construct by including some of meta tags. 
Note: the metadata output via this plugin applies to the entire site.
<h3>Donations</h3>
I created this plugin for my usage and decied to share with the WP community. I completely use the Head Meta Data WordPress plugin. 
Send some stars to Jeff Starr.
Links, tweets and likes as you want …

Head Meta Date

Head Meta Date adds a set of date <meta> tags to the <head> section of all posts & pages. This is a fork from http://wordpress.

Multisite wp_head Code vs Head Meta Date