channeleaton

For large multisite installations of WordPress, it’s easy to let user management go by the wayside. Many times we forget to disable or remove old user accounts, leaving our sites open to users who are no longer part of our organization.
Mass-Disable Users (MDU) aims to fix that.
MDU allows super-administrators to disable old users while retaining all of the author information. This is especially important for news sites.
How does it work?
MDU takes a list of email addresses (in CSV format) and compares it to the existing WordPress users database then any users who do not exist in the CSV file are demoted to Subscriber in every blog!
NOTE: This plugin only works on multisite!

Mass-Disable Users plugin for WordPress

Allows network admins to disable users via CSV while retaining all author information.

scribu

AppThemes

With the current WordPress administration area, the only way to add existing users to a certain blog is by entering their usernames, one by one. It’s very time consuming.
With this plugin, you can do it in bulk, by using the familiar “Change role to…” dropdown:
<ol>
<li>Go to WP Admin -> Users.</li>
<li>Click the “Entire Network” link.</li>
<li>Check the users you want to add.</li>
<li>Choose the new role from the dropdown.</li>
<li>Press “Change”.</li>
</ol>
Note that you have to be a super-admin to be able to do this.

User Management Tools

Allows super-admins to quickly add users to a particular blog in a multisite installation.

Mass-Disable Users plugin for WordPress vs User Management Tools