Every once in a while a WordPress admin comes across a plugin that makes them wonder how they lived so long without it - this is one of those plugins.
I work for a large academic institution using WordPress, BuddyPress and Multisite to provide a social network that helps facilitate sharing and communication across faculty, student and administrator groups. The amount of plugins and themes in our install had become so large that we were beginning to have trouble maintaining them all. After reviewing and installing Network Plugin Auditor, it only took about 30 minutes to identify and remove the unused themes and plugins on an install with 3,627 users, 1,192 sites, 231 plugins and 264 themes.
At 363 lines of code in a single file, this plugin should be used as an example to all other plugin authors of how to properly write a WordPress plugin. It's simple, powerful, does one job and does it well. I noticed only a slight degradation in page load time on the Network Plugins page, and that is mainly due to that fact that it doesn't use pagination. All other pages augmented by this plugin show only enhanced features.
If you administer a large Multisite install with a growing number of themes and plugins, this plugin is a must have. It's one of those plugins that makes you jealous that you didn't think of it yourself.