Los Angeles Stars Signing Off Social Networking Sites For Charity November 28, 2010 / 8:37 AM PST / CBS News (credit: Kevin Winter/Getty Images) Kim Kardashian (credit: Michael Loccisano/Getty Images) Khloe Kardashian (credit: Jacob Andrzejczak/Getty Images) Justin Timberlake (credit: Andrew D. Bernstein/NBAE via Getty Images) Alicia Keys (credit: Stephen Lovekin/Getty Images) Usher (credit: ROBYN BECK/AFP/Getty Images) Ryan Seacrest (credit: Jason Merritt/Getty Images) Serena Williams (credit: Mike Ehrmann/Getty Images) Jennifer Hudson (credit: Roger Kisby/Getty Images) Elijah Wood (credit: Andrew H. Walker/Getty Images for MONTBLANC) Janelle Monae (credit: Ben Gabbe/Getty Images)