When Britney Spears bombed at the 2007 VMAs with a lackluster lip-synched “Gimme More,” the poor performance was so disappointing because awards-show stages were once the place where Spears defined herself so memorably (and successfully). Click here to check out more than a dozen of her performances at the Grammys, Billboard Music Awards and more (including her iconic, slithery “I’m a Slave 4 U” from the 2001 VMAs, above). Want more? Click here for our guide to Spears’ entire music-video catalog, here for a photo timeline of her entire career and here for a facebook of the people in Britney’s ever-changing universe. An excerpt of our current Spears cover story can be found here.