If you have a page with some different pieces content on it
like

• ads
• top-Menu
• site menu
• crossselling items
  etc.

The usage of these content pieces could be tracked via https://piwik.org/docs/content-tracking/

To make your website better it would be not only interesting which content pieces are a) seen and b) used, but on the other site:
which pieces of content are never or only very rarely a) seen b) used

This may have several reasons:

• they are not visible to the user (design problem)
• there could be a technical problem (technical problem: maybe only in some browsers)
• no one needs them (content problem) ...

To find these pieces of content it would be very helpful to have the possibility to find & show them in an automatic way via "Invers content tracking"

one way may be

• to call all pieces of content to say "hello - I do exist" to piwik (some kind of crawler)
• compare these pieces of contents with the statistics piwik have from content tracking
• show a list per page with the pieces of contents never or only rarely seen and one for never/rarely used
  (maybe with a customizable filter..)