The 2008 Z100 Jingle Ball

Christmas came early for the lucky fans who scored tickets to New York City radio station Z100's annual Jingle Ball. Though there wasn't a single holiday carol to be heard, Madison Square Garden rocked with crowd-pleasing beats from David Archuleta, Ne-Yo, and Katy Perry. In the H&M Artists Lounge, Rihanna and Kanye West caught up before going their separate ways-she joined boyfriend Chris Brown for a steamy duet, while he had the crowd singing along to his latest hit, "Love Lockdown." "I'm really excited!" said Rihanna of the night of chart-topping performances, which raised funds for Stand Up To Cancer.

"I'd like to thank Z100 for messing up my life," said Katy Perry-dressed in full sexy Santa apparel and backed up by a band of dressed as holiday elves-before leading the crowd in a sing-a-long of her 2008 anthem, "I Kissed a Girl."

"This is my first time at Madison Square Garden," admitted California boy Brody Jenner. After picking up a $500 gift card and VIP shopping membership to H&M in the retailer's Artists Gift Lounge, Jenner hit the stage to introduce a performance by Leona Lewis.

Neither Nick Lachey or High School Musical star Ashley Tisdale sang for the crowd at Madison Square Garden, but both hit the stage to introduce the performers on the bill. "I have a single coming out in January 2009 and then an album in March, so definitely look for me at the 2009 Jingle Ball," declared Lachey.

Natasha Bedingfield

and Leona Lewis helped Katie Couric get the word out about Stand Up To Cancer at the H&M Artist Gift Lounge. Part of the proceeds from the Jingle Ball were donated to the cancer research through the charity.

Jesse McCartney

caused the crowd-which consisted mostly of tween girls-to go wild when he hit the stage to perform. "We keep it simple for these holiday shows," said McCartney of his onstage ensemble.

New York City native Lady Gaga chatted with Brandy before checking out items from BlackBerry, Canon and Dooney & Bourke in the H&M Artists Gift Lounge. "The Jingle Ball was the very first concert I ever saw, back in 1998," said the "Just Dance" singer, whose stage style included her trademark lash extensions.

Project Runway

winner Christian Siriano donated some pedal power when he hopped aboard the Duracell Snowmobike, which will power the 2009 sign in Times Square on New Year's Eve. Other health-conscious celebrities who stopped by the gift lounge received one-year memberships to the New York Health and Racquet Club.

Peter Facinelli

sampled some of the make-your-own soft drinks at the Soda Stream table in the H&M Artists Gift Lounge. "I came to see Paramore perform, but I missed them," said the Twilight star, who was mobbed by fans backstage.

"Every night I like to try something different," said Chris Brown, who gave the crowd something they hadn't seen before when he called upon girfriend Rihanna to help him sing a few songs.