Plugins are modules (.NET assemblies to be precise) which run inside of FogBugz to change or add to the look and feel and functionality of the application. The robust plugin architecture allows you to make changes to all areas of FogBugz: cases, wikis, discussion groups, email handling and time tracking. Plugins can add all new pages and tools to FogBugz or change existing interfaces such as the case view. Plugins can even create new APIs to allow connections to other applications.
You can browse the Plugin Gallery, or install one locally from a different source. If you don't find the functionality you need, try writing your own in your favorite .NET language.
FogBugz 7 comes with six great plugins with many more to come both from Fog Creek and developers like you:
Plugins can be enabled or disabled by FogBugz administrators by clicking the "yes" or "no" link in the Enabled column on the plugins admin page, accessible by clicking Plugins from the Admin menu. Disabling a plugin preserves its data in the FogBugz database in case you need to enable it again later. For information on adding and removing plugins completely, see Installing Plugins.
Once installed, plugins are configured via the "Configure" icon next to their names on the Plugin admin page. The icon only appears next to plugins that have configurable options.