A few years ago, Jennifer Lopez's career seemed to be floundering.  Not any longer, she's now topped Forbes magazine's annual list of the 100 Most Powerful Celebrities,displacing last year's #1, Lady Gaga.

According to Forbes, once J-Lo landed the American Idol judging job, it revived her career and gave her a platform to build her empire.  She now has big endorsement deals with L'Oreal and Gillette, a clothing line at Kohl's, a fragrance line, and another show, Q'Viva!, with her ex-husband Marc Anthony.  She also has a strong social media presence, with 12 million Facebook fans and 6.6 million Twitter followers, and she's reportedly earning $20 million for her second season on Idol.

Justin Bieber is #3 on the list, right behind Oprah Winfrey. Not only did he earn $55 million from touring and record sales and rack up 21 million Twitter followers, he's also a venture capitalist, having invested in several technology startup companies.

Rihanna is #4 on the list, thanks to her non-stop stream of hit singles, her touring income, her endorsement deals with Nivea and Vita Coco, her Rebl' Fleur fragrance, and her 53 million Facebook fans.

Lady Gaga is #5.  Her slide from #1 is due to the end of her most recent tour, but she stays in the top 10 thanks to her album sales and social media influence: she's got more Twitter followers than anyone in the world.

Britney Spears is #6, thanks to her successful tour of last year, her album sales, her endorsement deals and her fragrance line.  Katy Perry's #8, due to the fact that she scored five #1 singles from one album, she's only the second artist in history to do that, next to Michael Jackson, as well as her successful tour.  Both Britney and Katy also landed high on the list due to the number of mentions they got in the media, mostly due to their personal lives: Britney got engaged, while Katy got divorced.

Other musicians who made Forbes list:

#11 --Taylor Swift
#16 -- Beyonce
#17 -- Elton John
#21 -- Paul McCartney
#24 -- Adele
#25 -- Bon Jovi
#26 -- Dr. Dre
#38 -- Jay-Z
#42 -- Sean Diddy Combs
#45 -- Kanye West
#69 -- Lil Wayne