According to the AP, papers have recently been released that tell about another American intelligence agency that operated in the 1940s and 1950s:
Created during World War II as a purely U.S. operation free of the perceived taint of European allies, the Pond existed for 13 years and was shrouded in secrecy for more than 50 years. It used sources that ranged from Nazi officials to Stalinists and, at one point, a French serial killer.
It operated under the cover of multinational corporations, including American Express, Chase National Bank and Philips, the Dutch-based electronic giant. One of its top agents was a female American journalist.
The rest of the article contains information on some of the exploits of the organization, how it was founded, and how it ended.
While leaked emails about Journolist or leaked documents through WikiLeaks may be interesting, the information contained in the archives of the United States government and all its agencies would be fascinating.