Peace's first link (As of 1997) detailed US nuclear weapons, here's what else is suspected of existing officially, starting with who holds the most (Correct as of 2002 - Source, Natural Resources Defense Council):

Russia (Formerly USSR): 7,200 Active - 16,000 Total
United States of America: 5,735 Active - 9,960 Total
Peoples Republic of China : 400 Active
France: 350 Active
UK: 200 Active
India: Between 40-50 Active
Pakistan: Between 24-48 Active
North Korea: Between 0-10 Active

Of the above only Russia and the United States have subjected their nuclear forces to independent verification under various treaties and agreements.

Numbers above detailed as 'Active' indicate total number that make up the stockpile of operational weapons per country, not the number of operational weapons deployed for use by that country. The balance of the total (i.e. Total - Active) are weapons that exist and are stockpiled awaiting dismantling and destruction.

Israel does not appear in the above list of nuclear armed countries although it is suspected that Israel may possess somewhere between 100 and 200 nuclear weapons. This however has never been either confirmed or denied by the Israeli Government. The estimates of the number of weapons that Israel might possess is based upon the amount of fissile material which has likely been produced, and the amount of fissile material needed per warhead depends on estimates of a country's proficiency at nuclear weapon design.