Superstar DJ Samantha Ronson hosted the über-private Celebrity Karaoke at the Heineken Green Room on Sunday night, as Hollywood's elite belted out their favorite tunes while DJs Kelly Cole and Jus Ske spun on the ones and twos. Ronson kicked off the night with "Wind Beneath My Wings." Bijou Philips then impressed with her rendition of "You Ain't Woman Enough," her first impressive performance of many, and Sienna Miller followed soon after with "These Boots Are Made for Walkin'." Fisher Stevens was a frequent half of duet performances, both with Tim Hutton and Donovan Leitch, with whom he belted out a heartfelt and humorous "Ground Control to Major Tom."

Matisyahu brought the house down with his take on "No Woman No Cry," adding a personal touch of freestyle action at the end that drew cheers, while Josh Hartnett and Matt Leinart made more than a few hearts flutter with their version of "Good Vibrations," before which Josh declared he could "throw a ball better than Matt." Hartnett also channeled Elvis with a cover of "Hound Dog," while female admirers snapped photos. P. Diddy and Harvey Weinstein chose to remain spectators, chatting in a private banquette near Drea de Matteo, Shooter Jennings and Gina Gershon. Gershon also gave two performances, and Jena Malone impressed with her rendition of Peggy Lee's "Fever" and Marcy Playground's "Sex & Candy," during which she dropped to her knees. Paul Rudd, Emile Hirsch, Winona Ryder, Robin Wright Penn and Ryan Reynolds enjoyed the ambience from off-stage, and the party went strong until 4am.