Official website of the Israeli postal authority and its philatelic service.
There are in Israel around 25 collectors' club, as well as some youth clubs. There are also some national associations that deal with specialized philately. All these organizations come under the umbrella of the Israel Philatelic Federation, a non-profit organization. The site provides much useful information about Israeli philately, including an illustrated catalog of Israeli stamps and a catalog of commemorative cancels.
The Society of Israel Philatelists (SIP) was founded in New York City shortly after Israel became a sovereign state (1948). The SIP us devoted to the philately of the Holy Land, Israel and Judaica. The Israel Philatelist is the society's journal that is sent to 1,500 members worldwide.
Wikipedia page providing an overview of Israeli stamps and postal history.