Content Type Explorer App
I've just released a new SharePoint-Hosted App on CodePlex https://sptoolbasket2013.codeplex.com/releases/view/91909.
Sometimes we need to delete content types but we don't always know where they are used. Because you cannot delete a content type that is still in use, this App helps finding which lists and/or child content types make use of a given content type.
Here are some screenshots:
The App is localized in French & English and will be available soon on the SharePoint Store.