Charles Fulton

This plugin suppresses features of the Multisite site creation process:
<ul>
<li>It suppresses the welcome email sent to new site administrators on site creation</li>
<li>It cancels the site creation process if the given email does not exist, instead of creating a local user</li>
</ul>
It also flushes rewrite rules on site creation to address https://core.trac.wordpress.org/ticket/20171.
<h3>Privacy</h3>
This plugin neither collects nor stores any personal, private, or identifying information about any user.

Site Creation Utilities

This plugin improves the Multisite site creation process by eliminating undesired features.

Emanuela Castorina

This plugin in a multisite installation shows the ID of the current site/blog in the admin bar menu. The ID of the current site/blog is linked to the site info page. 
It adds also a custom column with site id information inside the sites list table. 
It can be installed only on a multisite.

Wp Show Site ID

This plugin in a multisite installation shows the ID of the current site/blog.

Site Creation Utilities vs Wp Show Site ID