It scans your WordPress database and shows what various things old plugins (which were deactivated or uninstalled) left in it. Cleanup is available.
Attention! Starting from version 0.9.2 plugin works with WordPress 3.0 and higher only. For earlier WordPress versions use plugin version 0.9.1 from http://downloads.wordpress.org/plugin/plugins-garbage-collector.0.9.1.zip 1. Deactivate plugin if you have the previous version installed. 2. Extract "plugins-garbage-collector.x.x.x.zip" archive content to the "/wp-content/plugins/plugins-garbage-collector" directory. 3. Activate "Plugins Garbage Collector" plugin via 'Plugins' menu in WordPress admin menu. 4. Go to the "Tools"-"Plugins Garbage Collector" menu item and scan your WordPress database if it has some forgotten tables from old plugins.