BuddyPress.org

In the database (preferably with something like PHPMyAdmin) you can look at the table wp_signups under the column “active.” That’s WPMU. In WP you can look at the wp_users table. If I remember right, it just changes user_status.

I don’t know of a plugin that’s pulled this information. @boonebgorges has talked about a plugin that would do close to this including resending the activation email and clearing out ones that didn’t activate, but otherwise I don’t know a plugin that will do this.