We have mentioned the Foreign Relations of the United States (FRUS) many times in this blog, but other countries have similar series of diplomatic editions as well. (N.B. All these series, due to declassification procedures, have at least 30-year lags in the coverage.) We are limiting ourselves to those available in English and online: Documents on Australian Foreign Policy now number over thirty volumes beginning with 1937, including monographic titles; Documents on Canadian External Relations have the first two volumes covering events from 1909 through 1919 at this site while this site contains volume 12(1946) onward; and Documents on Irish Foreign Policy begins with 1919. Sadly, the Documents on British Foreign Policy have very few volumes online.
English-language Diplomatic Editions