Hometown: Brooklyn, NY
Why they matter: Bandleader David Longstreth, a Yale music-composition grad, combines everything from tribal African hollers to classical violins on his band's experimental new album, Bitte Orca.
You should know: Longstreth penned an experimental work for Bjork recently, and the two performed it at New York City's Housing Works Bookstore Café. Read a review here.
LISTEN: Dirty Projectors w/ Bjork live, "Mount Wittenberg Orca"

Hometown: Brooklyn, NY
Why they matter: Bandleader David Longstreth, a Yale music-composition grad, combines everything from tribal African hollers to classical violins on his band's experimental new album, Bitte Orca.
You should know: Longstreth penned an experimental work for Bjork recently, and the two performed it at New York City's Housing Works Bookstore Café. Read a review here.
LISTEN: Dirty Projectors w/ Bjork live, "Mount Wittenberg Orca"

Hometown: Oslo, Norway
Why they matter: Four ladies who thrash banjos, pluck fiddles, and bang marching drums, garbage cans, and cookie jars (!) like Appalachian witches drunk on White Lightning. If their live set is as raucous and fun as their sound, prepare for a crazed Bonnaroo hootenanny.
You should know: The word "katzenjammer" is German, meaning "discordant sound" -- and is also sometimes used to indicate a general state of depression or bewilderment.
LISTEN: Katzenjammer, "A Bar In Amsterdam"

Hometown: Paris, France
Why they matter: This slick band's new album, Wolfgang Amadeus Phoenix, is all the rage. Their combination of Strokes guitar jangle, Air-like ambience, and Maroon 5 pop groove scored them a performance on SNL -- and they were excellent!
You should know: Frontman Thomas Mars has a child with his partner, Sofia Coppola, director of films like The Virgin Suicides and Lost in Translation.
LISTEN: Phoenix, "1901"

Hometown: Brooklyn, NY
Why they matter: MGMT may be the most Bonnaroo-appropriate band on the bill: These merry jesters flaunt an unwashed yet fashionable look, are in with the hipsters and the hippies, and will bring their danceable, psychedelic sound to Bonnaroo primetime -- a 2 A.M. slot that's sure to be one of the festival's biggest parties.
You should know: MGMT just released a music video for their track "Kids," starring none other than quirky singer/harpist Joanna Newsom as a negligent mother. Check it out here.
LISTEN: MGMT, "Kids"

Hometown: Burlington, VT
Why they matter: Festivals like Bonnaroo were built on the massive, traveling fanbase of jambands like Phish. And now, after a five year break, they're back to headline not one but two nights. Grab a hula hoop, a glow stick, or a pair of glass juggling balls -- and boogie down!
You should know: The Mockingbird Foundation, a non-profit organization run by Phish fans, mailed a $1,000 check to a music education program in every city on the band's Summer 2009 tour -- including the Coffee County Red Raider Band Boosters in Manchester, TN (Bonnaroo's hometown).
LISTEN: Phish, "Waste"

Hometown: Burlington, Vermont
Why she matters: The siren ditches the New Pornographers, retreats to the woods with her pets, listens to the Band -- and forges a glorious mix of gothic country and gospel sounds. Her music doesn't just matter -- it's essential.
You should know: Case's new album, Middle Cyclone, features cameos by Calexico, M. Ward, and the New Pornographers -- and received 4.5 stars from SPIN.
LISTEN: Neko Case, "Maybe Sparrow"

Hometown: Los Angeles
Why they matter: Like Tribe Called Quest? How about Pharcyde? Then you MUST hear the flowing, laid-back rhymes and sampled beats of this duo -- one of the best acts in hip-hop's underground.
You should know: For P.U.T.S.' latest album, Fun DMC, the boys captured the real L.A. -- taking mics around town to record the sounds of house parties, planes flying overhead, and ice cream truck jingles.
LISTEN: People Under the Stairs, "The Wiz"

Hometown: Athens
Why they matter: These psychedelic crazies take David Bowie's Ziggy Stardust shtick deep into outerspace by sporting animal costumes and multi-colored capes and headdresses, and playing an experimental power-pop that uses the Thin White Duke's rock sound as a launch pad into epic and improvisational jams!
You should know: Frontman Kevin Barnes performs under the guise of Georgie Fruit, his cross-dressing African American alter-ego.
LISTEN: Of Montreal, "Id Engager"

Hometown: Nigeria
Why he matters: Like Paul Simon, Vampire Weekend, and Talking Heads' multi-culti dance sound? Well, meet King Sunny Ade, a seasoned guitar virtuoso and a pioneer of Juju music -- a combination of western electric guitar and synths with traditional African rhythms.
You should know: King Sunny Ade isn't just musical royalty -- he's a member of one of Nigeria's royal families.
LISTEN: King Sunny Ade, "Ja Fun Mi"

Hometown: Brooklyn, NY
Why they matter: If Spoon moved to Jamaica and recorded a new album, the result could be It's Frightening, White Rabbits' just-released second record, produced by Spoon frontman Britt Daniel. It's a winning mix of rock, pop, and reggae.
You should know: White Rabbits recently played a stripped-down set at the SPIN office in NYC. Click here to watch!
LISTEN: White Rabbits, "Percussion Gun" Live on Letterman

Hometown: Eau Claire, Wisconsin
Why they matter: Heartbroken and in need of a shoulder to cry on? Try For Emma, Forever Ago, Bon Iver mastermind Justin Vernon's lovelorn 2008 debut -- one of the most touching, emotive albums in recent memory. His latest release, the Blood Bank EP, is similarly moving.
You should know: Bon Iver is a take on the French phrase "bon hiver," which translates to "good winter." Vernon wrote the songs for his debut in a remote cabin in Wisconsin in the winter.
LISTEN: Bon Iver, "Skinny Love"

Hometown: Atlanta
Why they matter: Combine T. Rex's cocksure glam, Cheap Trick's crunchy power-pop, and the Beach Boys' sunny psychedelia and you get Paris, the excellent debut album from this Southern band.
You should know: Kuroma mastermind Hank Sullivant is the founding bass player of the Whigs. He has also performed and toured with longtime pals MGMT.
LISTEN:Kuroma, "In New York, Everything Is Tropical"

Hometown: Los Angeles (via Cleveland, OH)
Why they matter: If Trent Reznor's goal is to scare the bejesus out of his fans at each live show, mission accomplished. His band of industrial warlords -- even after 20 years -- pack a punch, delivering menacing beats and static-y chaos with psychotic fervor.
You should know: See 'em now: Reznor claims NIN is on their last tour EVER.
LISTEN: Nine Inch Nails, "March of the Pigs" Live

Hometown: El Paso, TX
Why they matter: This energetic group create the sonic equivalent of an epileptic seizure. They combine salsa grooves, punk ferocity, screeching saxophones, and experimental rock guitars into a frenetic show that's as must-see as it is must-hear.
You should know: Band co-founders guitarist Omar Rodríguez-López and vocalist Cedric Bixler-Zavala are also original members of defunct but beloved post-hardcore band At the Drive-In.
LISTEN: The Mars Volta, "Teflon"

Hometown: Los Angeles
Why they matter: Attention fans of Tom Petty and Neil Young: This fivesome channel the American greats in dusty acoustic ballads with searing electric riffs and poetic lyrics about wide-open spaces and love lost. And with vet session musician Russell Pollard (Sebadoh, the Folk Implosion, the Watson Twins) at the forefront, Everest put on an excellent, emotive show -- a festival must!
You should know: Neil Young was so impressed with Everest's sound that he signed them to his label, Vapor Records, and hand-picked the band to open his 2008 tour.
LISTEN: Everest, "You Ain't Goin' Nowhere" feat. Jim James

Hometown: Toronto
Why they matter: The documentary about these Canadian metal men is one of the year's best, and it'll be playing in the comfy (and air-conditioned!) Bonnaroo Cinema during the festival. The film tracks the long-forgotten group as they pursue stardom… even at the age of 56. It's hilarious and moving -- and it rocks!
You should know: In their '80s glory days, Anvil opened for Bon Jovi, the Scorpions, and Whitesnake, but never found similar success -- until now.
WATCH: Anvil! The Story of Anvil Trailer

Hometown: Long Beach, CA
Why he matters: No rapper epitomizes summer quite like Mr. Snoop Dogg himself -- the SoCal thug knows how roll with the top down, mix a mean gin'n'juice, and party 'til the break of dawn. Don't forget the blunt wraps!
You should know: Last year, Snoop Dogg became the first mainstream American artist to appear on a Bollywood soundtrack, contributing the title track to the film Singh Is Kinng.
LISTEN: Snoop Dogg, "I Walk The Line" (Johnny Cash Remix)

Hometown: NBC's kennel
Why he matters: This trash-talking, cigar-smoking pup (who made his debut in 1997 on Late Night with Conan O'Brien) is far from domesticated -- he poops on even the biggest politicians' and celebrities' heads. He'll be hosting a variety show called "Bonnapoo" at this year's festival, so no one's safe from his snarky bark.
You should know: Though Triumph and Eminem famously duked it out at the 2002 MTV Video Music Awards, the two have since become allies, with Triumph appearing in the rapper's 2005 "Ass Like That" music video.
Watch:

Hometown: Freehold, NJ
Why he matters: For more 35 years, the Boss has tapped into America's consciousness, writing passionate songs about working class despair, the loss of childhood innocence, and spirited romantic groping in the back of a four-on-the-floor Chevy. But onstage he preaches the gospel of transcendence, presenting those songs in sweat-soaked, three-hour sets.
You should know: Springsteen won a Golden Globe for the song "The Wrestler," his contribution to the film of the same name, starring Mickey Rourke.
LISTEN: Bruce Springsteen, "The Wrestler"

Hometown: Bamako, Mali
Why they matter: Playing guitar is hard enough -- but try fingering the same dazzling riffs as Amadou... then try doing it without the benefit of eyesight. This duo, who met at a school for the blind in Mali, mix Middle Eastern and Latin sounds with yearning vocals (in more than three African languages!) into a style that's been dubbed "afro-blues."
You should know: The duo will be the opening act on Coldplay's U.S. tour next month.
LISTEN: Amadou & Mariam, "Sabali"

Hometown: Chicago
Why they matter: With their June release, Wilco (The Album), these Midwesterners have crafted their best record yet by balancing the studio wizardry of their 2002 classic Yankee Hotel Foxtrot with the stripped down sound of 2007's Sky Blue Sky. That, and guitarist Nels Cline's playing is entertaining in itself.
You should know: Wilco (The Album) features a duet between frontman Jeff Tweedy and "1234" singer Feist!
LISTEN: Wilco, "Impossible Germany" Live at Bonnaroo '07

Hometown: New Orleans
Why they matter: Imagine Gogol Bordello's raucous party remagined by a dance club DJ. Ben Ellman, better known as the sax man in Galactic, combines the old and new worlds, mashing ethnic Balkan music with banging hip-hop beats.
You should know: Ellman is also a founding member of an eight-piece Yiddish funk ensemble called the New Orleans Klezmer Allstars.
LISTEN: Here.

Hometown: New York City
Why he matters: Without the creative Talking Heads singer, bands like MGMT, CSS, Klaxons, Natalie Portman's Shaved Head, or pretty much any other new experimental dance group probably wouldn't exist -- and that would make for a pretty damn boring Friday night.
You should know: Byrne just released Everything That Happens Will Happen Today, his first collaboration with producer/Roxy Music keyboardist Brian Eno in 18 years!
LISTEN: David Byrne and Brian Eno, "Strange Overtones"

Hometown: Oakland, CA
Why they matter: Imagine Metallica and Motorhead's classics played in fast-forward. That's what this trio sounds like: an aggressive assault led by frontman Matt Pike's frightening roar.
You should know: High on Fire worked with Nirvana producer Jack Endino on their most recent studio album, 2007's Death Is This Communion.
LISTEN: High On Fire, "Rumors of War"

Hometown: Brooklyn, NY
Why they matter: Giraffes' brand of snarling '70s-style rock recalls greats like Led Zeppelin, Thin Lizzy, and Black Sabbath. And they're dangerous live -- known for moshing with the audience, taking shots between songs, and hurling microphones and instruments off stage.
You should know: Lead singer Aaron Lazar has a rare heart condition that once put him into sudden cardiac arrest twice in six hours.
LISTEN: The Giraffes, "Man U"