Who knew the Moulin Rouge-era "Lady Marmalade," which pointed to the past in so many ways, would become such a prescient harbinger of the future? The year was 2001, and to promote his long-awaited followup to Romeo + Juliet, Baz Luhrmann rounded up a pop-star Avengers of sorts to sing a 27-year-old disco hit that had already been recorded several times over. Christina Aguilera, Lil' Kim, Mya, and Pink assembled to wail away over Missy Elliott's hip-hop-infused production, donning cabaret lingerie and prancing through a video at least as memorable as any scene from the film, and it was enough to send the new "Lady Marmalade" to #1 for five weeks on the strength of radio airplay alone. The song wasn't released as a standalone single for purchase, and neither the iTunes store nor commercial streaming services were in the picture yet, but if streaming had been available back then, people would have streamed "Lady Marmalade" so much -- which brings us to our present situation.