This creates a link to maps on categories and articles
With the "level=" parameter, it displays coordinates from subcategories as well: e.g. level=2.
With the "uk=" parameter, a link to an OS (Ordnance Survey) map is displayed. Any non-empty value in the field will display the link, e.g. "uk=y". This is currently not available in combination with "level="
You can activate an additional tab in Special:Preferences (see Gadgets) to display a map link on all categories.