Plugins

For WordPress MultiSite installs, allows accurate and private system crontab requests instead of classic WP-Cron.

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

Ticket support system for multisite network.

This plugin adds a TOS (Terms of Service) field on the multisite signup form. (Such as wordpress.com TOS field)

Provides a system for registration requests and their processing in multisite. Two-level moderation.

WP3.1 multisite "mu-plugin" that allows you to add a user to all sites or no sites. Just drop in mu-plugins.

Automatically add users to peer blogs in a multisite network.

Simply add widgets in order to link another blog in a multisite instance

This plugin adds a coffee cup ratio widget to: Appearance > Widgets

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