Irish Stamps is a business within An Post, the Irish Post Office, and is the official source for all Irish postage stamps, and a wide range of books, prints, stamp booklets and other products.
The Eire Philatelic Association is a non-profit philatelic organization, based in the U.S., that specializes in the collecting, study, and enjoyment of stamps and other postal items of Ireland.
Wikipedia page providing a useful overview of Irish stamps and postal history.
Recent news about Ireland stamps, from StampNews.com.
GB Overprints Society page showing GB stamps overprinted for use in Ireland.
Wikipedia listing of people depicted on the stamps of Ireland, with links to biographical data.
The philatelic story of WWII censorship of Irish mail during the period known in Ireland as "The Emergency" 1939-1945.
This page give the historical background to the partition of Ireland in 1922, a brief synopsis of the Civil War, and describes (with illustrations) the stamp issues of the Provisional Government and of the IRA.