Ke$ha, April 17, 2010

The Performance: For smash 'Tik Tok,' Ke$ha wore an American Flag cape and danced with a bunch of space people. For 'Your Love Is My Drug,' she and her band became Day-Glo natives of some sort. Neither did much to distract from her shaky vocal adventures, though. Many critics consider Ke$ha to be one of the worst musical guests of all time.

Career Impact: Her performances tend toward the uneven, bizarre and ill-advised, but Ke$ha knows her way around a hook. Being one of the most infamous acts to ever grace the 'SNL' stage hasn’t stopped the sing-talker from penning some insanely catchy ditties, and it definitely hasn’t stopped her fans from making them major hits. Not only has Ke$ha experienced post 'SNL'-success with her own singles 'We R Who We R' and 'Blow,' she’s also scored a major hit with a little song she wrote for Britney Spears called 'Till the World Ends.'