I'm not sure if I can commit to a definite best song of the 00s, there's been a lot of good stuff this decade! Here are six of my favorites:
"Xerox My Hand"—Kill Me Tomorrow
"Pilot"—The Notwist
"Float On"—Modest Mouse
"I Want Wind To Blow"—The Microphones
"Staring at the Sun"—TV On the Radio
"Destroy Everything You Touch"—Ladytron