Europe is in a debt crisis, the Middle East is shaking, and there's market panic at home. It is against this backdrop that we present the world's 100 most powerful women.

The women on this annual list were chosen not just for being on top, but for being smack in the middle of Richter-registering events -- and more.

Their power derives from money and might, yes, but also (thanks to old and new media) from reach and influence.

Image: German Chancellor German Chancellor Angela Merkel © Michele Tantussi, Bloomberg, Getty Images

Angela Merkel

This year's No. 1 in the ranking, German Chancellor Angela Merkel -- recognized as the leader of the European Union -- is key to curing what ails the eurozone.

As the Arab Spring turns into the autocrats' summer, second-ranked Secretary of State Hillary Clinton provides encouragement to dissidents, while Facebook's Sheryl Sandberg (No. 5) and Twitter's Katie Jacobs Stanton (No. 56) empower the rebels storming the barricades with a steady stream of news -- and ways to report on the action in 140 characters or less.

Rep. Michele Bachmann, R-Minn., (No. 22) is battling it out in the 2012 presidential race, while Sarah Palin (No. 34) remains a force in politics despite her decision to sit out a White House run next year.

We have lots of business leaders too: women from Silicon Valley, Wall Street and Main Street; entrepreneurs of import, like HTC's Cher Wang (No. 20) and media marquise Arianna Huffington (No.31).

The women on the list include many newsmakers, yes, but some are custodians of the news. Jill Abramson, the new executive editor of the New York Times, makes her debut on list at No. 12. BBC News, run by Helen Boaden (No. 51), reaches some 34 million viewers weekly. Probably better known, though, are the televised journalists: ABC News' Christiane Amanpour (No. 44) and Diane Sawyer (No. 47), Ann Curry of NBC's Today (No. 66) and Greta Van Susteren (No. 75) of Fox News.

Image: Lady Gaga © The Sydney Morning Herald, Fairfax Media, Getty Images

Lady Gaga

Other famous faces make the list this year because they have exploited their celebrity status to build global businesses or champion humanitarian causes. Lady Gaga (No. 11) raised more than $200 million to fight HIV/AIDS, while Angelina Jolie (No. 29) continues her work as a U.N. ambassador.

The United Nations placed two women on this year's list: Josette Sheeran (No. 30) of the World Food Programme, the world's largest humanitarian agency, and Helen Clark (No. 50) of the U.N. Development Programme. Other nonprofit leaders include CARE USA's Helene Gayle (No. 36) and Judith Rodin (No. 71), the president of the 98-year-old Rockefeller Foundation.

Of the women on the list, 10% have bank accounts in the 10 figures, including self-made multimillionaires Oprah Winfrey (No. 14) and J.K. Rowling (No. 61). These billionaires do more than just eat bonbons: Wal-Mart Stores (WMT, news)heiress Alice Walton (No. 85) is opening her pre-eminent collection of American art to the public with the Crystal Bridge Museum on 11/11/11, while Georgina Rinehart (No. 19), the richest woman in Australia, is using her wealth to campaign against environmental reforms and taxes.

There's nothing static about the list. Nearly half of the women are first-timers or are back after dropping off. Some changed jobs since the previous year. Most were promoted, but some changed tracks altogether or are newly elected to office -- all evidence that women are moving up the pipeline.

Image: Christine Lagarde © PAUL J. RICHARDS, AFP, Getty Images

Christine Lagarde

Christine Lagarde (No. 9), formerly France's finance minister, for example, is now managing director of the International Monetary Fund in Washington, D.C., and Ngozi Okonjo-Iweala (No. 87) switched from a job at the World Bank to finance minister of Nigeria. Dilma Rousseff (No. 3) and Yingluck Sinawatra (No. 59) were elected president of Brazil and prime minister of Thailand, respectively. They join a club of eight heads of state on the list.

Our members come from politics, business, technology, media, entertainment and nonprofits and were ranked by three metrics: dollars, media (traditional and social) and power base.