POTW: Justin Bieber & Selena Gomez, Lady Gaga, Lil Wayne
Rihanna throws a rocker-growl to the audience on on NBC's "Today" in Rockefeller Plaza on May 27, 2011 in New York.

In the Social 50 chart's top 10 this week, Rihanna climbs 4-2 thanks to the buzz surrounding the release of her latest music video, "Man Down." The clip, which premiered on June 1, has brought in 12 million Vevo views (earning a 51% week-over-week gain).

In the short, the singer literally guns down a man in the dramatic opener. As the story develops, viewers learn that he had sexually assaulted her in a dance club the previous night.

The Social 50 ranks the most active artists on the world's leading social networking sites - YouTube, Vevo, Facebook, Twitter, MySpace and iLike -- using a formula blending weekly additions of friends/fans/followers along with weekly artist page views and weekly song plays.

Meanwhile, alt-rockers Linkin Park ascend 25-17, thanks to the heat generated by their involvement in the summer blockbuster film "Transformers: Dark of the Moon." Their video for the single "Iridescent" -- also featured on the movie soundtrack -- racked up 1.8 million YouTube views since its June 3 release. In it, many visuals from the "Transformers" sequel are used, which peaked interest among both fanbases.

Due to the serious, rescue nature of "Transformers: Dark of the Moon," the film's music director chose "Iridescent" -- a hopeful, yet somber and harmonic ballad -- to set the tone for the movie.

In the tracking week, Linkin Park also saw a 30% increase on Twitter, gaining 10,500 followers.

With the premiere of their latest single "Every Teardrop Is A Waterfall," coldplay/401639">Coldplay also soars up the Social 50 tally (38-27). The upbeat song quickly gained 3.6 million YouTube views. "Teardrop" -- the first song off the band's forthcoming new album -- debuts at No. 17 on the Hot Digital Songs chart and at No. 29 on the Billboard Hot 100.

Rapper Wiz Khalifa hurtles 26-19, with a boost of 792,000 YouTube views. His new video for the stoner-friendly anthem "Reefer Party" -- featuring Chevy Woods and Neako -- debuted last week. In it, party scenes laced with bongs and blunts are tied together with comical interludes with Khalifa acting as a sarcastic, pot-smoking thug (think: Tony Montana meets comedian Dave Chappelle).

Coincidently, Kid Cudi (48-38) also released the video for his latest single "Marijuana," which starts with him lightly singing, "Pretty green bud, all in my blunt." So far, it has pulled in 423,000 Vimeo views. While two songs share subject matters, they couldn't sound more different. Cudi takes a melodic, chill-out approach while Khalifa clearly took the bass-driven, party banger route.

This week's biggest chart drops: Jennifer Lopez (16-28) and Tiesto (24-34) crashed down, while the Beastie Boys fell completely off. Each suffered declines in activity across all monitored sites.

The rest of the top 10: Lady Gaga (No. 1) and Eminem (No. 6) hold their positions, while Justin Bieber (3-2), Shakira (5-4), Akon (3-5), Don Omar (8-7), Lil Wayne (9-8), Katy Perry (10-9) and Beyoncé 7-10 all make slight moves.