Maxaud

(NOTE: Before saying this plugin is broken, please understand what this plugin does. It’s meant for WordPress installs that have multiple NETWORKS.)
Adds the ability to have different themes available to different NETWORKS in a multisite atmoshpere.
WordPress allows for multiple “networks”, these are not to be confused with sites. A network holds blogs underneath of it.
This plugin will allow you to separate themes into different directories so they’re only accessable and viewable to the networks you choose.
The plugin will attempt to create a directory in the /wp-content/ directory named /ms-themes/. If it fails to create it, then you will need to make one.
In the /ms-themes/ directory you will create a folder for each network that you want to allow only certain themes to.
Example: 
If you have a theme named “Snarfer Theme”, and you want to only allow it to be viewable/available to the network (and all sites on that network) with the site_id of 7, you would place the snarfer theme directory in /wp-content/ms-themes/7/
Future releases:
<ul>
<li>Network option to turn off auto creation on/off network directories, index.php files.</li>
<li>Network option to display network ID in the footer of sites so network admins can easily tell what network a site is under.</li>
</ul>

Multisite Themes

Adds the ability to have different themes available to different NETWORKS in a multisite atmoshpere.

fritsjan

With this plugin you can simply batch create / add a bunch of sites to your WPMU install (WordPress Network) and use one of your existing sites as a template for the new sites. The existing blog will be cloned exactly including posts, layout, settings, etc. The plugin also takes care of domainmapping the newly created sites. (depends on ‘WordPress MU Domain Mapping’ by Donncha to be installed)
This plugin will save you a lot of time. 
Even adding one site is faster with this pluging compared to the normal way: add site, domainmap it, set everything up.
Update: You can now also use it without domainmapping, so just cloning sites in a batch! Insert the name of the subdir or subdomain you want to make in the place of the url.

Add Clone Sites for WPMU (batch)

Batch add new sites on Wordpress MU / Wordpress Network while using a template site to clone, includes batch domainmapping of the new sites.

Multisite Themes vs Add Clone Sites for WPMU (batch)