Jay-Z, Vampire Weekend Kick Off Soggy All Points West
Fleet Foxes performs at All Points West on July 31, 2009.

Fleet Foxes make their debut on the Social 50 chart, arriving at No. 48. The Seattle-based folk rock group made impressive gains on Facebook (40%) and Twitter (78%), with a weekly total gain of 16,000 fans and 2,100 followers, respectively. In support of their second album, "Helplessness Blues," Fleet Foxes made their first U.S. TV performance on "Late Night With Jimmy Fallon" on May 20.

Fleet Foxes Bring a Quiet Riot to NYC's United Palace

After making huge climbs in previous weeks, both Adele (11-23) and Deadmau5 (15-27) suffered setbacks in views, with each seeing an 11% decline in week-over-week views. In a similar fashion, Beastie Boys also lost energy in their race to the top 10, falling 23-37. A fall in YouTube (down 26%) and MySpace views (down 38%) helped worsen the tumble.

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.

Selena Gomez moves 18-16 this week on the Social 50 thanks to a 2.17 million gain in Vevo plays (up 340%). Her latest single "Who Says" (with the Scene) has brought in a massive 34 million plays and is bulleted at No. 19 on the Pop Songs chart. Last week she was in the news thanks to her shooting the last scenes for her hit Disney series "Wizards of Waverly Place," the release of her "Teen Vogue" cover and her Billboard Music Awards smooch with Justin Bieber.

Billboard Bits: Pink Blasts Selena Gomez's Pink Ponies

Pop-punk starlet Avril Lavigne (12-13) also obtained a rather large play increase (71%) this week. Her catchy, upfront single "Smile" has added 2.6 million Vevo plays since May 18.

Likewise, LMFAO (24-21) acquired the biggest week-to-week fan boost (146%), adding 220,000 Facebook Likes. Close behind is Enrique Iglesias (30-25), who increased 87%.

Michael Jackson gains a top 10 post, moving 21-10. The late pop icon amassed 465,000 Likes on Facebook, a 50% week-over-week increase. As for the rest, Lady Gaga (No. 1), Justin Bieber (No. 2), Rihanna (No. 3), and Shakira (No. 4) hold steady, while Akon (6-5), Eminem (5-6), Beyoncé (8-7), Katy Perry (7-8), and Lil Wayne (9-10) mix up positions.

Notable re-entries: Metallica (No. 47), Nickelback (No. 45) and Mariah Carey (No. 50).