Rapper 50 Cent and veteran modern rock act Green Day were the toast of Las Vegas last night (Dec. 6), as each nabbed six trophies at the 2005 Billboard Music Awards. Mariah Carey won five awards, whil

Rapper 50 Cent and veteran modern rock act Green Day were the toast of Las Vegas last night (Dec. 6), as each nabbed six trophies at the 2005 Billboard Music Awards. 50, who was the top finalist with mentions in eight categories, was honored as artist of the year and took the album of the year prize for "The Massacre," while Green Day earned rock artist of the year and woon rock song of the year for "Boulevard of Broken Dreams."

Mariah Carey, who was a finalist in seven categories, won five awards, while "American Idol" Carrie Underwood and Shakira each took home three. The show was broadcast live on Fox from Vegas' MGM Grand Garden Arena and hosted by artist/actor LL Cool J.

50 Cent's awards were rounded out by R&B/Hip-Hop, Rap and Hot 100 artist of the year titles and the ringtone of the year award for "Candy Shop" featuring Olivia. In Paris and unable to attend, 50 Cent was informed of his feats via a cell phone call from LL Cool J.

Green Day, who opened the show with a performance of "Holiday," also won pop group, Billboard 200 album group, Hot 100 group and modern rock artist of the year awards. Bandleader Billie Joe Armstrong was additionally charged with presenting the Century Award, Billboard magazine's highest honor, to Tom Petty.

"I love music, I love rock and roll, therefore I love Tom Petty and the Heartbreakers," Armstrong said. "If you're going to come up [on stage] and thank God, thank God for Tom Petty."

"We haven't always been boy scouts, but we never lost sight of the music," Petty said in accepting the honor. After thanking many who have been involved in his 30-year career, he added, "Let me remind you that this ain't the end. I can still kick some ass."

Carey capped her 2005 comeback by being named the female Billboard 200 album artist and female R&B/Hip-Hop artist of the year. Her long-running No. 1 single "We Belong Together" earned her the Hot 100 song, Hot 100 airplay of the year and rhythmic top 40 title of the year awards.

Among Underwood's honors was the top-selling Hot 100 song of the year award for "Inside Your Heaven/Independence Day," while Shakira's awards included the Latin pop album artist of the year trophy.

No Doubt singer Gwen Stefani won the new artist of the year award on the strength of her solo debut, "Love.Angel.Music.Baby," while her single "Hollaback Girl" was the digital song of the year. Stefani called up collaborator Pharrell to the stage to accept the latter award with her.

Toby Keith won both awards for which he was a finalist: country artist and country albums artist of the year. He was among the show's performers, belting out the new song "Let's Get Drunk and Be Somebody" backed by a large band that included a horn section.

Reggaeton sensation Daddy Yankee also won two trophies, including Latin album of the year for "Barrio Fino" (El Cartel/Machete), as did Mario for his single "Let Me Love You," including R&B/hip-hop song of the year.

Though he's just two albums into his solo career, Kanye West was honored for his significant success with Billboard's Artist Achievement Award. "When I first came out I was a hot head -- I thought I was the greatest," he said in accepting the trophy. "I still think I'm the greatest."

Other performances were turned in by Underwood, Ciara, Stefani with Slim Thug, Daddy Yankee with Pharrell, Ashlee Simpson with Pretty Ricky.

R. Kelly, who performed earlier in the show by a pool filled with scantily clad dancers, led the show's finale, "Let Your Light Shine," a song he wrote as a tribute to Gulf Coast hurricane victims as part of the "Come Together Now" relief project. Kelly was joined by a chorus, a cast of dancers and most of the evening's participating artists, all dressed in white.

Billboard Music Awards are based on sales data compiled by Nielsen SoundScan and radio information monitored by Nielsen Broadcast Data Systems. Winners are determined by the 2005 year-end charts, which reflect the weekly charts published from December 2004 through November 2005. Billboard compiles more than 250 recap charts for its annual Year In Music issue, which will hit newsstands Dec. 16.

Click here to view the full list of 2005 Billboard Music Awards winners.