Pictures Celebrity Fashion Lines March 28, 2011 / 10:33 AM EDT / CBS News Credit: Donald Bowers/Getty Images Beyonce Knowles Credit: Will Ragozzino/Getty Images Jay-Z Credit: John M. Heller/Getty Images Mary-Kate and Ashley Olsen Credit: Stephen Lovekin/Getty Images Sean 'Diddy' Combs Credit: Ethan Miller/Getty Images Jessica Simpson Credit: Jamie McCarthy/Getty Images Hilary Duff Credit: Alberto E. Rodriguez/Getty Images Mandy Moore Credit: Toby Canham/Getty Images Emma Watson Credit: Ian Gavan/Getty Images Justin Timberlake Credit: Florian Seefried/Getty Images 50 Cent Credit: Rob Loud/Getty Images Alyssa Milano Credit: Michael Buckner/Getty Images Pharrell Williams Credit: Mark Mainz/Getty Images Avril Lavigne Credit: Craig Barritt/Getty Images Lauren Conrad Credit: Jason Merritt/Getty Images Joan Rivers Credit: Valerie Macon/Getty Images Rachel Zoe Credit: Matthew Peyton/Getty Images Whitney Port Credit: Frazer Harrison/Getty Images Serena Williams Credit: Jeff Gross/Getty Images Russell Simmons Credit: Matthew Peyton/Getty Images Sienna Miller Credit: Jason Merritt/Getty Images Lindsay Lohan Credit: Andrew H. Walker/Getty Images Madonna Credit: Bryan Bedder/Getty Images