In case your study of history hasn't included places like Alaouites or Trebizond, Linn's provides descriptions of some of the more than 700 entities that at some point have issued postage stamps. Postal Administrations of the World Check out Linn's comprehensive list of the world's postal administrations and their addresses. Whether dollars, lira, or rubles, Linn's currency guide can help you make heads or tails out of stamp denominations. If you are looking for a postal history society, Linn's list is a good place to start. If you are looking for local stamp clubs in your area, Linn's list is a good place to start.
Many European cities have their own weekly stamp markets.
In this story from Scotland resident James Carson, he gives the date, time and location of these markets. Linn's Stamp News, of Sidney, Ohio.