"Ground Zero" simulator
Software based on Google's Maps framework and a bit of Javascript, gives impression
on effects of a nuclear attack of any given point.
Effects of Nuclear Weapons published by the US Government is by far the most authoritive official unclassified
source. Most other sources are based on compilations from this book.
Out-of-print editions (1962, 1964, 1977) are still available from
Amazon, eBay etc. Recently (in 2006), the 1977 edition was re-published by Knowledge Publishers.
The Effects of Nuclear War report was prepared by Office of Technology Assessment of the US Congress in 1979.