We decided a few years ago that flags would be too political, but we've since added areas with relationships between them so I think we should reconsider it. Some other sites show flags (e.g. Rate Your Music and Musik-Sammler.de) too.
The userscript I made is at http://userscripts.org/scripts/show/38668 but it keeps breaking when we change things on the website so it would be nice to have it more integrated.
I would only include them for things we have marked as countries and not all areas. There are other tickets for always showing the country.