The peerless duo began their ascendance in the late '90s with a few party-themed hits: Ol' Dirty Bastard's "Got My Money" (1999), Mystikal's "Shake Ya Ass" (2000), and Jay-Z's "I Wanna Love U" (2001). The Neptunes crossed over from rap to pop in 2001 and began producing tracks for the likes of Britney Spears ("I'm a Slave 4 U"), *NSYNC ("Girlfriend"), and Usher ("U Don't Have to Call"). In addition to these pop stars, the duo continued producing hits for the biggest names in rap, working with everyone from LL Cool J ("Luv U Better") and Busta Rhymes ("Pass the Courvoisier") to Bow Wow ("Take Ya Home") and Nelly ("Hot in Herre"). Furthermore, the Neptunes began their own rap-rock group, N.E.R.D., and presented the hardcore rap duo Clipse. By this point, the duo comprising the Neptunes -- Pharrell Williams and Chad Hugo -- had become the pop-rap industry's most demanded producers, on a par with other big-name producers like Dr. Dre and Timbaland, if not perhaps even supplanting them for a moment in time. Their debut album, Neptunes Present... Clones (2003), confirmed their across-the-board popularity, topping Billboard's album chart and moving roughly 250,000 units during its first week. Amid all of this success, they continued to churn out hits, most notably alongside Justin Timberlake ("Rock Your Body") and Snoop Dogg ("Beautiful") as well as for their longtime standbys (Jay-Z's "Excuse Me Miss") and even themselves (Pharrell's "Frontin'"). ~ Jason Birchmeier