renanivo

Adds some Multisite-specific functions to WordPress’ XML-RPC interface (http://yourdomain.com/xmlrpc.php).
Using this plugin, you can create a blog, update the archived status and get a blog ID using a remote software (another server, a desktop software, a mobile software…)
The functions enabled by this plugin are:
<ul>
<li>Create Blog (ms.CreateBlog)</li>
<li>Get Blog Id (ms.GetBlogId)</li>
<li>Update Archived (ms.UpdateArchived)</li>
</ul>
refer to the <a href="http://wiki.github.com/renanivo/WP-Multisite-XML-RPC/" rel="nofollow ugc">wiki</a> for further documentation

Multisite XML-RPC

Adds some Multisite-specific functions to WordPress' XML-RPC interface.

Rob Scott

The XMLRPC Pingback Ping can potentially be used as part of a DDOS attack. 
If you do not need the functionality, this plugin will use core functions to disable it.

Eazy XMLRPC Pingback Disable

This plugin disables the WordPress XMLRPC pingback ping.

Multisite XML-RPC vs Eazy XMLRPC Pingback Disable