Billboard Bits serves up the best bite-sized nuggets of music news and gossip.

Rihanna To Serve as 'X Factor' Guest Judge?
Rihanna will reportedly join fellow female pop divas Paula Abdul and Nicole Scherzinger on the upcoming U.S. version of "The X Factor." The singer will serve as a guest judge after a similar stint on the U.K. 'Factor' last year. ( TMZ)

Jim Carrey Sings Radiohead's 'Creep'
Jim Carrey sang Radiohead's hit "Creep" for a delighted crowd at Arlene's Grocery, a bar in New York City during the city's annual Fashion Week. Watch the actor (who recently professed his love for Emma Stone in another odd viral video) in action:

Blink-182's DeLonge Loses Voice, Gets Help from Tourmates
blink-182 called on its Honda Civic Tour mates for a little help on Sunday night [Sept. 11] at the DTE Energy Music Theatre in suburban Detroit. After guitarist Tom DeLonge lost his voice to a cold, the group brought on Matt & Kim to help with "Always" -- Matt Johnson sang it ("A dream come true," he gushed), while Kim Schifino "booty danced" around the stage. Then My Chemical Romance's Gerard Way took lead vocals on "First Date," which prompted blink's Mark Hoppus to crack to DeLonge that "the show gets a little better when different people sing your songs...It's been good playing in a band with you, but Gerard, let's start something rad!" DeLonge, meanwhile, conceded several times that Way "is SO good looking!" blink nevertheless delivered its full 90-minute set, with DeLonge croaking his way through the other songs. 

Nas To Release Memoir
Nas will release his first memoir, "It Ain't Hard to Tell," in fall of 2012 through Atria/Simon & Schuster Books. The MC will cover his rise through "Illmatic," his beef with Jay-Z, his past relationships, and everything in between. (RapRadar)

The National Announces Tour
The National, still riding high on the success of 2010's "High Violet," will hit the road this fall for trips to Japan, Australia and North America. The Walkmen, Neko Case and Local Natives are among the acts supporting the tour, which kicks off on Nov. 6. (Pitchfork)

(Reporting by Jason Lipshutz and Gary Graff)