Here is an animated map by Japanese artist Isao Hashimoto showing the test sites and originator countries of the 2,053 nuclear explosions during the period 1945-1998 (via Boing-Boing):
Some interesting facts:
Explosions by countries - USA 1032 (including Hiroshima & Nagasaki), USSR 715, France 210, UK 45, China 45, India 4, Pakistan 2.
The explosions peaked during the 1960s and gradually slowed down in the 1990s.
I wonder what permanent damages the holed up test sites have done to the world?