Upon taking up residency in the White House, a president also assumes a tidy salary of $400,000 a year, plus extra cash for expenses. That's certainly not the kind of change you'd find under most couch cushions, but it's not such a princely sum that the president will be set for life when leaving office. While many leaders are either independently rich enough or old enough that they just retire after leaving office, others are desperate to make a buck or a pound. So how do ex-presidents and other former world leaders support themselves as they while away the autumn of their years?

The Very Broke Harry Truman:

When Truman's presidency ended in 1953, he headed home to Independence, Missouri, but there was a nagging problem: he didn't have any money.Â His business interests from prior to his political life hadn't generated any sort of savings for him, and he thought that taken a corporate position or endorsing products would cheapen the presidency. His only income was a $112-a-month army pension, so he did what former presidents now do without thinking:Â he sold his memoirs. Truman received a $670,000 deal for the two-volume memoirs, but after taxes and paying his assistants, he only netted a few thousand dollars on the project. Things got so dire that Congress passed the Former Presidents Act in 1958, which gave retired commanders in chief pensions of $25,000 a year.Â At least his health insurance was eventually covered; when Lyndon Johnson signed Medicare into law in 1965, he presented President Truman and his wife, Bess, with the first two Medicare cards.

Jimmy Carter:

Carter famously rose to the presidency from humble roots as a Georgia peanut farmer, but when he assumed office he placed his business and farming issues in a blind trust to avoid any potential conflicts of interest. It was a noble act, but it didn't play out so well for Carter; when he resumed control of his assets, he was a million dollars in debt. He needed dough, so he started writing. And writing. Although he's known for his work with Habitat for Humanity and his willingness to go on global diplomatic missions, Carter is a shockingly prolific author of over 20 books. Some of his tomes are standard memoirs and political texts, but Carter's also penned children's books, a volume of poetry, a historical novel, and Bible-study guides.

Bill Clinton:

Bill Clinton pulls in $250,000 to give a speech, which has been a fairly lucrative racket for him. A 2007 report in the British newspaper The Independent estimated Clinton's earnings from speeches alone at somewhere in the neighborhood of $40 million since he left office six years earlier. Clinton also sold his memoir My Life to Knopf for $15 million, and he serves as an advisor for the private equity firm Yucaipa Companies, a post that has pulled in at least $12.6 million. When the Clintons released their tax data in April 2008 as part of Hillary's campaign disclosures, they showed income of $109 million since leaving the White House.

Margaret Thatcher:

Although declining health has slowed her down lately, Thatcher was fairly busy after stepping down as Prime Minister in 1990. She remained in the House of Commons until 1992. She received the title Baroness Thatcher that year, which got her a spot in the House of Lords. Thatcher also penned a two-volume memoir, The Path to Power and The Downing Street Years, which hit the New York Times' best-seller lists in 1993 and 1994. On top of that, she served as Chancellor of the College of William and Mary from 1993 to 2000 and penned the international relations text Statecraft:Â Strategies for a Changing World in 2002. All of this work must have left Thatcher pretty set; after all, she has given Cambridge two million pounds to endow a chair in her name.

John Major:

Thatcher's successor as Prime Minister has had a decidedly more low-key life since leaving the post in 1997. As an avid cricket fan, he served as the president of the Surrey County Cricket Club from 2000 to 2001 and has been on the Committee of the Marylebone Cricket Club since 2005. He also joined the private equity firm the Carlyle Group's European Advisory Board in 1998 and supposedly rakes in 25,000 pounds for each speech he gives on the lecture circuit.

Tony Blair:

Like Bill Clinton, Blair got a book advance that ensured he wouldn't have to hit up any of his friends for a pound or two from time to time. In October 2007 the New York Times reported that Random House purchased Blair's memoir for a staggering $9 million. Or rather, they purchased the rights to the memoir once it's written; despite receiving the gigantic advance, Blair's spokesman admitted that the former Prime Minister hadn't gotten a chance to "put pen to paper" when he signed the deal. On top of the sweet advance, Blair's also pulling in cash as an advisor on climate change for Zurich Insurance and as a senior advisor for JPMorgan, both of which have been reported as six-figure-a-year jobs. He's also making 500,000 pounds for a series of speeches and will teach a course on faith and globalization at Yale this year.