Her recording career hasn't done so bad either, although her first self-titled album came out in the midst of personal tragedy -- a short time after it was released, her mother, sister and nephew were murdered in Chicago. The album sold a respectable 800,000 copies and earned her a Grammy.
Hudson has also scored lucrative endorsement deals with Gap, Avon and currently Weight Watchers, after shrinking from size 16 to size 6.
As the first rocker to rise on "Idol," Bice showed a lot of promise, but he was ultimately bested by season four winner Underwood.
Bice's first album, "The Real Thing," released in December 2005, reached No. 4 on Billboard's Top Albums chart, and he seemed off to a good start, appearing with Willie Nelson and recording with Carlos Santana.
But a life-threatening intestinal condition sidelined him, and Bice never seemed to get back on track. He recently released his third album on an independent label and continues to tour.
McPhee has had a disappointing recording career since coming in second to winner Taylor Hicks.
But that hasn't stopped her from becoming a fixture on the entertainment scene. The Los Angeles native has appeared in People magazine and Teen Vogue, and co-starred in the film "The House Bunny."
By far, Daughtry was the biggest success to come out of season five. He didn't make it past fourth place, but he has easily surpassed winner Hicks.
His debut album outsold Hicks' album -- 5 million to 700,000, respectively. Together, his two albums have sold 6 million copies in the United States, according to Nielsen SoundScan.
Today, he commands stadium-size concerts and has become a fixutre on radio and television.
Season six saw a drop in the ratings for "Idol." It's no wonder then that neither Lewis nor winner Jordin Sparks have made much of a splash since then.
While Sparks appears to be growing her fan base, beat-boxing Lewis has for the most part faded into obscurity. His first album reached No. 10 on the charts but sold a disappointing 350,000 copies.
After label Arista dropped him, Lewis recorded his sophomore effort, an electronica album for Tommy Boy Records.
Archuleta was16 when he was runner-up to David Cook in the battle of the Davids in season seven, so the jury is still out on his career.
Even though his first album did middlingly well, Archuleta has a strong fan base of tweens and teens. He's won several Teen Choice Awards and appeared on popular kids' shows such as "iCarly" and "Hannah Montana."
Lambert may have lost out on the title to Kris Allen last season, but he snagged the cover of Rolling Stone and continues to generate more buzz and album sales.
His censored performance at the American Music Awards earlier this year was widely talked about. But the controversy only seems to help Lambert sell more records.
His first album reached No. 3 on Billboard's 100 and has racked up 2.6 million downloads, easily making Lambert a millionaire. Next month, he launches his Glam Nation tour.