rfair404

This plugin makes it possible to have a menu that is controlled by the primary site but used throughout all other sites in the network.
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<li>When a navigation menu position has no menu assigned, the “fallback” defaults to pages. This plugin over-rides that so that instead it uses the nav menu from the “main site” (site ID 1)</li>
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Network Menu Fallback

Gives multisite administrators the ability to create menus that can be used throughout a network.

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.
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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.

Network Menu Fallback vs Root Relative URLs