From African leaders' credit card numbers to the friendships of British politicians, the WikiLeaks cables show U.S. diplomats left no stone unturned in efforts to gather information on friends as well as foes.
The released cables include requests for, and reports on, a range of subjects, from crop forecasts to military hardware purchases to social commentary, but put a particular focus on the activities of important figures.
"The intelligence community relies on State reporting officers for much of the biographical information collected worldwide," say several of the cables. "Informal biographic reporting via e-mail and other means is vital to the community's collection efforts."
Information requested includes organisation names and position titles, other details from business cards, e-mail addresses, websites URLs, credit card numbers, frequent flyer account details and work schedules.
Computer passwords were also requested along with biometric data -- although it is not clear for what purpose.
One cable released by Britain's Guardian newspaper from January this year shows a senior State Department official thanking the London embassy for information on a relatively junior opposition minister.
Shadow prison minister Alan Duncan -- now international development minister after May's general election brought in a Conservative-Liberal Democrat coalition -- is a former oil trader and one of a handful of openly gay senior politicians.
The State Department said it particularly welcomed information regarding his Middle East expertise and friendship with now-Foreign Secretary William Hague, who was forced to deny being gay earlier this year after newspaper reports he had shared a hotel room with an aide.
"Analysts found the... information particularly insightful and exceptionally well-timed as analysts are preparing finished products on the Conservative leadership for senior policymakers," said the cable.
The cable then requested further information including on Duncan's relationship with Hague and now-Prime Minister David Cameron, a view on what role he might play in a Conservative government as well as his further political ambitions.
Other leaked cables include requests for personal information on African leaders from the Great Lakes region and senior U.N. officials.
A cable from February 2010 giving an account of a meeting with Azerbaijan President Ilham Aliyev goes into frank detail on his appraisal of the relationship between Russian Prime Minister Vladimir Putin and President Dmitri Medvedev.
"(Aliyev) said he has personally witnessed Medvedev taking decisions that then required further approval before they were implemented," the cable read. "He said that there are signs of a strong confrontation between the teams of the two men, although not yet between Putin and Medvedev personally."
Aliyev would have assumed those comments would never become public, and some experts worry U.S. diplomats may now find their best contacts becoming much more guarded.
"Once the trustworthiness of the State Department as a reliable conversation partner erodes, it is most difficult to repair," said former CIA official John LeBeau, Professor for National Security studies at the George C. Marshall European Centre in Germany.
"As is the case in journalism and intelligence collection, diplomats must be able to demonstrate to sources that their revelations will be well-guarded."
Another document described by The New York Times cites a U.S. embassy cable raising the possibility that Libyan leader Muammar Gaddafi may have had a romantic relationship with his Ukrainian nurse, who is described as a "voluptuous blonde."
Former insiders say no one should be surprised at the depth of U.S. intelligence gathering. It is simply, they say, what governments do. "On what I've seen, the main surprise would be if the U.S. were not doing some of the things 'exposed' by WikiLeaks," said Alastair Newton, a former British diplomat and cabinet official who is now political analyst for Japanese bank Nomura.