Sean Fisher

We are going to enable the WordPress ping service for each site in a WordPress MU Network. This allows each site to have a different ping list. By default, you have no ping list for WordPress MU sites.
<h4>New</h4>
<ul>
<li>Nothing</li>
</ul>
<h4>Features</h4>
<ul>
<li>Enables the custom ping for WordPress sites in WP MU.</li>
<li>Individual site settings for WPMU.</li>
</ul>
<h3>Help</h3>
For help, checkout http://sean-fisher.com/plugins/

Enable Site Ping WPMU

We are going to enable the WordPress ping service for each site in a WordPress MU Network. This allows each site to have a different ping list.

Lars Koudal

PPinger helps you use your visitors to ping Pingomatic.com that your blog has been updated.
It randomizes between pinging a randomly selected amount of these RSS aggregators:
Weblogs.com 
Blo.gs 
Technorati 
FeedBurner 
Syndic8 
NewsGator 
MyYahoo! 
PubSub.com 
Blogdigger 
BlogStreet 
Moreover 
Weblogalot 
Icerocket 
NewsIsFree 
TopicExchange 
GoogleBlogSearch 
Spinn3r 
Bloglines 
PostRank 
SkyGrid 
Collecta 
Superfeedr
It is a good help for getting new blogs indexed.

PPinger

Pings your blog to Pingomatic using your visitors's IP's at random intervals.

Enable Site Ping WPMU vs PPinger