Hide controls on a publishing page

When you build publishing pages in Sharepoint Designer you may want to hide some fields while it's in read mode. I usually want to hide fields like "Archive date", "Target group" and so on, and to do that you simply put them in an Edit panel. Now the fields are visible in edit mode, but hidden in read mode. That's really neat, since it's ugly to have a lot of fields when the page is in read mode. But I still want to be able to use the content of those "hidden" fields to sort the pages, or to filter information. Useful!