Secure Invites is a Wordpress MU plugin that allows you to only allow invited people to sign up.
Wibstats is a Wordpress plugin that gives each blog in a Wordpress, Wordpress MU or BuddyPress installation their own visitor statistics.
Demo Data Creator is a Wordpress MU and BuddyPress plugin that allows a Wordpress developer to create demo users, blogs, posts, comments and blogroll
PerformerJS allows you to add really cool effects and features to your website by doing some simple editing of the HTML code in your pages.
Sitewide Newsletters is a Wordpress MU plugin that allows site administrators to send an email message to all users.
Simple user admin is a Wordpress MU plugin that gives site administrators a simpler interface to manage blogs and users.
Personal Welcome is a Wordpress MU plugin that allows site administrators to create and send personalised welcome messages to new users.