The Billboard Music Awards ceremony Sunday night featured a number of star-studded collaborations including Britney Spears and Rihanna performing the latter's hit single, "S&M," which kicked off the ceremony, and a collaboration between iconic rapper Snoop Dogg and Far East Movement.  But perhaps the most stunning duet was delivered when rapper Lil' Wayne joined soul legend Mary J. Blige onstage for a crowd-pleasing rendition of the latest single, "Someone to Love Me (Naked)" from her soon-to-be-released album.  Watch clips of the Spears/Rihann performance and Blige/Wayne collaboration below.