Are you using any calender that shows monthly events?i.e - Calender that shows - sports events (MLB\soccer\football\NHL) , political debateds, big confrences, and all other major events.
Sort of related to this, but I recently looked at www.calendarx.com for a project we are doing. That might help you.
We use DivvyHQ (paid service) to track content development. Its has a content dev calendar which we use extensively. As Hubspot users we are also starting to use their new calendar features to track larger campaigns and assets.