Marcus Downing

Sometimes you want the different sites on a multisite network to share their taxonomies. 
This plugin forces a child site to use its parent’s taxonomies instead of its own.

MU Central Taxonomies

On a multisite network, this makes a child site use the main site's categories and taxonomies instead of its own.

Bernhard Riedl

This plugin is a <a href="https://www.bernhard-riedl.com/2010/08/01/tagpages-tags-functionality-for-pages-in-wordpress-30/" rel="nofollow ugc">follow-up</a> to the post which I wrote <a href="https://www.bernhard-riedl.com/2007/10/06/wordpress-23-tagging-posts-and-pages/" rel="nofollow ugc">a few years ago</a>. – The idea was (and still is) to equip pages with <a href="https://en.support.wordpress.com/posts/tags/" rel="nofollow ugc">tags</a> and include their number in a combined posts and pages <a href="https://codex.wordpress.org/Function_Reference/wp_tag_cloud" rel="nofollow ugc">tag-cloud</a>.
TagPages is fully compatible with <a href="https://codex.wordpress.org/Administration_Over_SSL" rel="nofollow ugc">https/SSL/TLS-sites</a> and WordPress multisite network.
Plugin’s website: <a href="https://www.bernhard-riedl.com/projects/" rel="nofollow ugc">https://www.bernhard-riedl.com/projects/</a>
Author’s website: <a href="https://www.bernhard-riedl.com/" rel="nofollow ugc">https://www.bernhard-riedl.com/</a>

MU Central Taxonomies vs TagPages