babo2015

This plugin adds a new “Plugins” tab to the site edit screen where you can enable or disable plugins for this website. You may enable/disable one at a time or per bulk action. The site admin will only see plugins that are enabled for his site or for the entire network. He still can decide if he wants to activate it or not.
Finally you’ll be able to install plugins that do not show to every single website in your multisite network!
<h3>Enable/Disable plugins for selected sites</h3>
<ol>
<li>Visit Network Admin > Sites and click on the Edit link of one site.</li>
<li>Select the Plugins tab.</li>
<li>Click on the Enable/Disable link beneath each plugin name to enable/disable it for this site or</li>
<li>Select several plugins by checking the corresponding check boxes or all plugins by checking the checkbox in the table header an choose Enable or Disable form the Bulk actions dropdown menu. Then click Apply.</li>
</ol>
You cannot disable a plugin for a site as long as it is activated there.

Multisite Plugin Controller

Enable plugins for selected blogs only on multisite websites (similar to theme functionality)

MarcusPope

A WordPress plugin that converts all URL formats to root-relative URLs to enable seamless transitioning between staging/production host environments and debugging/testing from mobile devices, without the use of hackish tactics like textual find-replace strategies or risky hosts/NAT spoofing strategies.
With Root Relative URLs you can browse your development site from http://localhost/ or http://127.0.0.1/ or from a named network resource like http://mycomputername/ without worrying about links redirecting you back to your site’s URL.
This plugin also modifies the tinyMCE hooks so links and media embedded with built-in tools will only insert URLs from the first forward slash after the domain (i.e. the root of your site.) This means when you push content changes to a staging or production environment they are guaranteed to reference the correct target instead of accidentally referencing a production resource in development or, worse-yet, a development-exclusive resource in production.
It supports path-based MU Installations, but does not support domain-based MU sites due to architectural deficiencies in the WordPress core.
Version 1.5 fixes an infinite redirect problem that is a result of a core bug in WordPress. If you have problems with the <!–more–> tag or permalinks for custom post types, please read the FAQ or new Install Steps for support.
Version 2.2 allows for adding certain URL’s or partial URL’s to a blacklist, meaning I won’t use root relative urls, but dynamic absolute URLs instead for displaying content. This will fix problems with 3rd party plugins, and can be configured on the General Settings page.
<h3>Arbitrary section</h3>

Root Relative URLs

Converts all URLs to root-relative URLs for hosting the same site on multiple IPs, easier production migration and better mobile device testing.

Multisite Plugin Controller vs Root Relative URLs