Nicole Richie: Karaoke Queen

07/28/2006 at 06:00 AM EDT

All hail Nicole Richie! The Simple Life star has been ruling the scene Tuesdays at L.A. club Guy's hot new karaoke night. Recently, Richie and pal Lindsay Lohan hit the stage for Dr. Dre and Eminem's "Forget About Dre." "Just so you know, I'm black, so this is from my roots!" Richie yelled into her microphone. And when they poured their hearts out to the Journey classic "Don't Stop Believin,'" Mary-Kate Olsen, who sat nearby, held up a lighter concert-style. "They gave it their all and had a great time," says a clubgoer. (Maybe more than their all: Soon after, Lohan was hospitalized for dehydration).

A week earlier, Richie kicked off her stilettos for Vanilla Ice's "Ice, Ice Baby" while pal and celeb deejay Samantha Ronson (who hosts Guy's weekly karaoke event) danced backup. "Richie was rocking the stage with well-choreographed moves," says an observer. "The crowd was on their feet, cheering her on." Among her fans that night: Jared Leto and Joel Madden.

Mandy Moore and Andy Roddick

Ray Mickshaw / WireImage; Jemal Countess / WireImage

Mandy & Andy: Friendly Exes

Renee Zellweger and Kenny Chesney aren't the only celeb exes who are still on friendly terms: Mandy Moore and tennis star Andy Roddick, who broke up in 2004 after more than a year together, recently shared an intimate lunch at the poolside Backyard restaurant at L.A.'s W hotel.

Beating the California heat under an oversized canvas umbrella, Roddick and Moore were animated and close during their meal. At one point, two bikini-clad women sashayed past their table, catching Roddick's glance. But after Moore turned her head mid-sentence to see what caught his attention, she quickly engaged him in a conversation that brought his gaze back to her.

Could something more than friendship be brewing? Rumors have been circulating that the actress's relationship with beau Zach Braff is on the rocks. Stay tuned ...

• By MARY ACOYMO, MARGARET CHERNIN, KIMBERLY LANSING and MARISA LAUDADIO