They are not touring right now, but from their most recent tour in 2010 Beach House and Dum Dum Girls supported Vampire Weekend.
Camryn in the European leg of their tour 5 Seconds of Summer are supporting them in the Europe, America and Australia legs of the tour as well
chiddy bang
David guetta
Nicki Minaj is supporting the European leg of the loud tour.source: Wikipedia
Trey songz
Zarif is supporting Beyonce on her UK tour.
the cataracs and dev are supporting Usher's OMG tour in America April '11.. i don't know if this will be the same for the UK tour :$
Wonderland are supporting
Camryn in the European leg of their tour 5 Seconds of Summer are supporting them in the Europe, America and Australia legs of the tour as well
Louis XIV are supporting them, hope this was helpful.
willow smith is supporting him :)
Yes, as they are supporting One Direction in the Europe, Australia and American leg of their world tour Camryn is also supporting them in the European leg of their tour
Joe Jonas will be Britney Spears supporting act
MGMT
keri hilson
B.o.B.
Insync