Beyonce has fun with Alicia Keys backstage at Jay Z's Tidal launch

Who has the power to get Rihanna, Madonna, Beyonce, Nicki Minaj, Usher, Daft Punk, Arcade Fire, Jack White and Kanye West  all on one stage?  Jay Z,  of course. The stars aligned to launch new music streamingservice called Tidal, designedto rival Spotify. At a special event at New York City's Moynihan Station on Monday, the stars stoodunited and signed an unspecified "declaration" before Alicia Keysshared the artists' hope that Tidal will "forever change the course ofmusic history."

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Thoughthis first artist-owned platform for music and video is potentiallyhistory in the making, that didn't stop Beyonce from having some fun backstage. The pop star made silly faces forthe camera crossing her eyes and sticking out her tongue as she took a photowith Alicia and Nicki.

But, the 33-year-old washer usual sexy self wearing a black and white jumper with a plunging neckline. Toadd a little drama, she paired the flirty frock with a long black lace kimono and sky-high heels.

Madonna and Rihanna alsogot in the playful action. The two cuddled up to each other and the 56-year-oldeven stuck out her tongue as they posed for photos backstage. The party didn't end until well after 7 pm and VIPs celebrated with D'Usse and Ace of Spades.

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Monday'smegastar launch followed a huge social media push in which stars devoted theirTwitter and Facebook pages to promote Tidal. Kanye told fans, "Together,we can turn the tide and make music history. Start by turning your profilepicture blue. #TIDALforALL." A message on Madonna's Twitter pageread: "Music makes the people come together. Join Madonna and turn yourprofile picture blue. Do it for the music. #TIDALforALL."

Tidal waslaunched last October but was bought by Jay Z two weeks ago for $56 million.Unlike its rivals, it does not offer a free version; a standardsubscription is $9.99 a month, and there is a premium option availablefor $19.99.

Therapper's strategy also includes encouraging artists to lobby their recordlabels to give Tidal new music a week in advance of other services. Looks like this Tidal wave is going to be mega!

Click below for more pics from the Tidal launch:

Photo: Getty Images