Roots-rocker Ben Harper makes his debut on the Social 50 chart this week at No. 47, thanks to buzz derived from his recent promotion of his latest album "Give Till It's Gone." He appeared on both the "Late Show With David Letterman" Web concert series "Live on Letterman" (May 19) and its parent talk show on CBS. The week following, the live set list premiered on Vevo, pulling in nearly 500,000 plays, a 290% week-to-week increase. Shortly thereafter, Harper continued his talk show march, making back to back appearances on "The Tonight Show With Jay Leno" and "Conan" (May 24 and 25).
 
Likewise, heavy metal act Slipknot enters the tally for the first time -- though, not for pleasant reasons. Last week marked the anniversary (May 24) of the death of the late bassist Paul Gray, who passed away in 2010.

Slipknot Replaces Deceased Bassist Paul Gray

On May 23, Slipknot bandmate and drummer Joey Jordison posted a heartfelt letter to his fallen friend. In the coming days, several music news sites remembered Gray and for the first time since the tragedy his wife, Brenna spoke to Revolver. Though a sad week, Slipknot added 348,000 Facebook Fans (up 180% week-to-week) charted the group at No. 42.
 
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.
 
In under a month, Beastie Boys debuted at No. 44 (May 4), ascended to a No. 16 peak (May 11), and have since stumbled to 37-45. Across all monitored music outlets, the trio realized a continued decline in plays and views (down 10% and 30% week-to-week). On VEVO, their much-anticipated, star-studded video "Make Some Nose" stalls at a humble 1.6 million plays.
 
With the release of Taylor Swift's latest video "Story of Us" (May 25) -- her latest single from her album "Speak Now" -- the pop star gained 814,000 VEVO plays, humbly moving 17-15. Additionally, Swift garnered attention for her fundraising effort on May 21 in Las Vegas. There, she sold tickets to the final dress rehearsal for her Speak Now tour in order to raise money to benefit those affected by the deadly tornadoes in the South. Her tour launched on May 27 in Omaha, Neb.

Taylor Swift Gets Schooled About Love in 'Story of Us' Video

Latin singer Don Omar grabs his eighth top 10 single on the Latin Songs chart this week as "Taboo" vaults 12-6, helping him fly 33-8 on the Social 50. This huge move is mostly fueled by his 19% boost in MySpace plays, as well as his consequent gain of 409,000 Facebook Fans (up 96% week-to-week). The rest of the top 10: Lady Gaga (No. 1), Justin Bieber (No. 2), Eminem (No. 6), Beyoncé (No. 7), and Lil Wayne (No. 9) all hold their respective positions, while Akon (5-3), Rihanna (3-4), Shakira (4-5), and Katy Perry (8-10) shuffle up and down in this week's chart. 
 
Notable re-entries: Daft Punk (No. 40), My Chemical Romance (No. 49), and Bruno Mars (No. 50).