Make them do girly songs!
Cornflake Girl or Winter by Tori Amos
Its Oh so Quiet or Enjoy by Bjork (especially Enjoy, soooo awesome)
Torn by Natalie Imbruglia (how hilarious would that be?)
Orinoco Flow by Enya
Stupid by Sarah McLachlan
ooooh, just listening to it now, what about "uninvited" by Alanis Morisette? Muse would make it even more eerie and epic!
But on a more serious note....
Hold me, Thrill me, Kiss me, Kill me by U2. That song rocks.