Like the song goes, we all want to be billionaires - a million just doesn't cut it to be really exceptional in today's society. And it's not just a man's world anymore: there are more female billionaires adding to the list every day. Plenty of female billionaires inherited their fortune, but there are those few who earned their money by working for it. Here's a look at some of these self-made female billionaires, and what characteristics these exceptionally wealthy ladies have in common. (For more, check out What's Your Billionaire Age?)

IN PICTURES: Retire A Millionaire In 10 Steps

  1. Oprah Winfrey - Net Worth: $2.4 Billion
    Oprah Winfrey is likely America's best-known rags-to-riches story. Born in Mississippi, Oprah was shuffled around to live with grandparents, her mother and father, enduring poverty and hardship. After graduating from Tennessee State University, Winfrey started her broadcasting career in Nashville, then relocated to Baltimore and eventually settled in Chicago where Harpo Studios is located today. Her successful television show, magazine and TV network has earned her billions, with a net worth that's growing daily. She hit #400 on Forbes' 2010 World Billionaires list. (Learn more about the talk show queen in Measuring The "Oprah Effect".)
  2. Doris Fisher - Net Worth: $2.5 Billion
    Doris Fisher planted the roots for her fortune in 1969, when she opened the first Gap store in San Francisco. The brand has since grown - with some ups and downs - to an international jean magnate, with partnering brands Old Navy, Banana Republic and Baby Gap. Fisher, transferred her shares to her three sons in 2004, as did her husband. It took a lifetime of determination, but Doris Fisher is now one of the wealthiest women in America. She ranked #374 on Forbes' 2010 World Billionaires list.
  3. Zhang Xin - Net Worth: $2 Billion
    Who says there's no money in real estate? Zhang Xin is proving there's money to be made in property - billions in fact - even in China. She earned her degree at Cambridge University before starting Soho China to develop property in China, together with her husband Pan Shiyi. In 2005, Zhang Xin's husband transferred his shares in Soho China to her, bringing this 44 year-old's net worth to a cool $2 billion, and her 2010 Forbes' World Billionaire rank to #488
  4. Margaret Whitman - Net Worth: $1.3 Billion
    Meg Whitman planned to be a doctor when she went to Princeton. She even took many of the required classes, but then changed her mind and decided to study economics. After graduating in 1977, she continued her education at Harvard with an MBA and started her career at Procter and Gamble. (Whitman isn't looking to join Buffett's pledge anytime soon. Learn more in Billionaires Who Haven't Taken The Pledge.)

    Whitman worked for Disney, StrideRite and FTD before reluctantly taking on a job heading up marketing for a small start-up auction website. That small start-up became eBay, the auction giant we know today, and earned Whitman her billion-dollar fortune. She resigned from her position in 2008, and is pursuing her political passion in November 2010's election for California Governor for the Republican Party. She ranked #778 on Forbes' World Billionaire for 2010.

IN PICTURES: Celebrities With Big Dreams That Paid Off

  1. J.K. Rowling - Net Worth: $1 Billion
    "Find a day job," J.K. Rowling's publisher told her when her Harry Potter series finally made it to print. Writing children's books just wasn't enough to make a living was the consensus - a preconception Rowling would soon blow out of the water. Rowling wrote the first book in the popular series during her daughter's naps, living on the U.K.'s meager state benefits. "Harry Potter and The Philosopher's Stone" slowly garnered attention by winning awards, and was eventually published in the U.S. in 1998.

    The rest is history, with successful movies, and even a recent Harry Potter theme park opening At Universal Orlando. J.K. Rowling, once an unemployed single mother, now sits on a billion dollars. Not bad for making up stories about a young wizard. She ranks #937 on Forbes' World Billionaire list for 2010. (Learn more in From Poverty To Power: Celebrities Who Started With Nothing.)

The Bottom Line
All of these women have different and interesting life stories - but what do they have in common? Are there any secrets to their billion-dollar financial success us regular Janes can learn from? Two of these billionaire ladies, Zhang Xin and Doris Fisher, started a business with their husbands - a good way not to have to go it alone. Some, like Margaret Whitman, started with a good education and worked hard and made smart business decisions along the way.

The most interesting are the rags-to-riches stories of Oprah Winfrey and J.K. Rowling, who simply didn't let their lack of resources stop them. With a positive attitude, these women made their fortune on their own terms - by working really hard for it. Like Oprah Winfrey says of her success, "I feel that luck is preparation meeting opportunity." (For more, see 4 Careers Where Women Make More Than Men.)

For the latest financial news, see Water Cooler Finance: Mergers, Hostile Bids And SEC Probes.

Want to learn how to invest?

Get a free 10 week email series that will teach you how to start investing.

Delivered twice a week, straight to your inbox.