The unofficial leader of the Spice Girls, Geri Halliwell (pictured in London on Feb. 2) was also the first one to leave the splintering group. Her first two solo albums, Schizophonic (1999) and Scream If You Wanna Go Faster (2001) did well in the U.K. (though not in the U.S.). Her third album flopped in 2005, but the singer has successfully branched out into making yoga videos, writing children's books, designing clothing -- and even becoming a United Nations Goodwill Ambassador in support of women's health. Halliwell, 40, gave birth to a daughter, Bluebell Madonna, in 2006, and has never identified the father. Earlier this year, she began judging Australia's Got Talent.