The 2012 Coachella Valley Music and Arts Festival is currently underway, with the first weekend of the two-weekend event occurring on April 13-15. While there were stellar performances throughout the weekend, there were also lots of other stars -- including pop starlets Rihanna, Katy Perry and Kesha -- who attended the festival to take in the live music and amazing performances.

While Rihanna was originally supposed to just be attending this year's Coachella festival as a concert goer, the Bajan couldn't help but hop onstage for a surprise performance during Calvin Harris' set. Even though this was a huge surprise for festival attendees, the performance everybody was talking about came when Snoop Dogg and Dr. Dre took the stage with a hologram of late rapper Tupac Shakur. Rihanna was blown away by the ground-breaking live show, tweeting, "#TupacBACK #unbelievable #IWASTHERE #STORY4myGrandKidz."

Katy Perry also took in the live music, rocking out with blue hair during M83's performance, while Kesha partied it up with her security detail. Meanwhile, some other artists who entertained from the stage included David Guetta and Usher, Wiz Khalifa, Florence + the Machine, Gotye and Kimbra, Frank Ocean, and Tyler, the Creator. Check out all these pictures from Coachella 2012 and let us know who you would've liked to catch live in the comment section below.