WordPressMU Plugin Commander
I’m solidly impressed with the WPMU Plugin Commander. One thing that seemed odd to me about WPMU was that I either enable users to have plugin control, or NO ONE (not even the site admin) has the ability to enabled/disable plugins (without a lot of hacking).
This plugin provides a control panel where I can globally enable/disable plugins, set plugins to be auto-enabled for new blogs, and give users the ability to enable/disable only selected plugins.