Who Sees Ads for WPMU
A modified version of the brilliant Who Sees Ads plugin by Ozh to work with WPMU and specifically with Farms '100 big ones' theme pack.
This really is an amazing plugin as it allows you to set any number of rules to decide where you want to show ads - or, in fact, any piece of content - on your site and allows you to control these rules via site admin.
It also takes an immense amount of work to keep this operational and working just fine for WPMU - which is why it's here, we'll be donating a bug chunk of membership fees to Ozh as a result.
Please note that you need to be logged in off the root blog (i.e. logged into site admin in test.yoursite.org/wp-admin/wpmu-admin.php ) to access the options in Site Admin.