Our goal: create taxonomy driven pages used to aggregate documents and list items with the same metadata.
This ability to tag documents and list items has been crucial to the organization, aggregation and retrieval of content stored in SharePoint. This is especially true when SharePoint becomes the host for previously unstructured file containers like file shares. Being able to add a term as metadata to a document allows the retrieval of that data through mechanisms like SharePoint search, either by what's stored in the document or the metadata tag itself. For list items, this also means that content across lists, across content types and throughout the farm can be brought together quickly if they have been consistently tagged with meaningful metadata terms.
This metadata, however, can also be used to organize page content, even without using some of the new cross site publishing features in SharePoint 2013. A page in SharePoint is really just another document. It lives in a library, is based on a content type and can have custom metadata applied. So we can tag pages in the same way we can tag items and documents. This means that those pages may be brought back through search or aggregated by their metadata terms (maybe by using a Content Query Web Part).
So, if we create a custom page layout using the publishing infrastructure features, we can build a content type that contains a managed metadata field. We can tag that page with a term to be used behind the scenes, but we can also add that term as a content field to display in the body of the page as well. The metadata is there to help organize but also visually "tag" the page for all the world to see.
The end result is that pages are returned in search results based on taxonomy term values along with documents and list items. This also provides a way to create term driven pages used to aggregate data. If we have documents and items tagged as "sales related" or "marketing related" for instance, we can throw a Search Core Results web part on a page that is also tagged with the same term. The page itself is tagged with the same metadata, which we can display on the page. Since it is aggregating tagged content from a variety of lists and libraries, it can become the one stop shop for all items tagged with a particular term.