Jose Manuel Sanchez

Network Site Names lets you add custom site names to be shown in the admin bar menu. Site names can be used to identify each site with a different name while using the same Blog Title in the front end. This is useful for Multilanguage or Corporative networks where many sites may need the same title.
This plugin is so small and simple that it can be installed as a <a href="https://codex.wordpress.org/Must_Use_Plugins" title="Must Use Plugins" rel="nofollow ugc">Must Use Plugin</a> without having to worry about updates. Read the Installation section for instructions.

Network Site Names

This plugin lets you add custom site names to be shown in the admin bar menu.

jroakes

This plugin will give you the ability to pull up any (non-Super Admin) user and in one click add that user(with a global role) to all sites in your MU install. Likewise, if you want to remove a user from all sites it is one click as well. CAUTION: WordPress has an optional mechanism when deleting a user from a site that will allow you to assign that users posts to another user. I have ignored this for this release. Please take a DB backups until you are used to this plugin and Multi-Site.

Multi-Site User Replicator 3000

WP3.1 multisite "mu-plugin" that allows you to add a user to all sites or no sites. Just drop in mu-plugins.

Network Site Names vs Multi-Site User Replicator 3000