Official site of Eesti Post, the Estonian postal service.
Wikipedia page providing a useful introduction to Estonian stamps and postal history.
Wikipedia listing of people depicted on the stamps of Estonia, with links to biographical data.
Recent news about Estonia stamps, from StampNews.com.
All aspects of Estonian stamps and postal history. With great detail on varieties, proofs, forgeries, experts, rarities etc. Official site of The Estonian Philatelic Society in Sweden.