Jessica Simpson was a pop-star in the late nineties, running with the likes of Mandy Moore, Jennifer Lopez, NSYNC, and Britney Spears. Her first single was "I Wanna Love You Forever," debuting in 1999. The song saw success on the Billboard charts for a whopping 20 weeks, peaking at number three. She recently penned a book, titled "Open Book," which was released on February 4. But she recently opened up to Jimmy Kimmel about who her first celebrity crush was.