British soul singer Adele and party rockers LMFAO led the nominees for the upcoming Billboard Music Awards.  Billboard unveiled the list of nominees Thursday, and the ceremony is scheduled for May 20th at the MGM Grand in Las Vegas.  Adele led the pack with 18 nominations, with LMFAO close behind with 17.  Rihanna, who led nominees for the award show in 2011 last year with 18 nods, came in third this year with 13, while Lil' Wayne and Lady Gaga each garnered ten nods to round out the top 5.