The Bowery Ballroom was packed. The hip downtown Manhattan music hall had been sold out for weeks and fans stood outside begging for extra tickets. Inside, the raucous crowd waited for the show to start, chanting for the performers backstage.

The concert, though, was created purely out of thin air — because this was the U.S. Air Guitar Championships, where last week 15 contestants with such stage names as The Godfather of Air and Thunderpants the Destroyer took to a barren stage, bereft of ... instruments.

"It's as close as you can get to being a rock star, without shlepping gear," said master of ceremonies Bjorn Turoque (pronounced "Born to Rawk").

The rules for air-guitar competition are simple:

• The guitar (which can be acoustic or electric) must be "invisible."

• "Air bands" are not allowed.

• "Air roadies" are OK.

• You can use a real pick.

The rest is an exercise of imagination — and for many, it's serious business. Thirteen of the 15 contestants have won their respective regional contest; one qualified from a VH1.com contest and another was the collegiate champ. The winner is sent to the world championships Sept. 6-8 in Oulu, Finland — a place spoken of with hushed reverence in air-guitar circles.

A panel of four judges score the air guitarists on an "Olympic figure skating scale" (6.0 being best) based on technical prowess, stage persona and a more opaque quality known as "airness."

Bjorn, whose real name is Dan Crane, explains to the crowd: "Airness is like pornography. You know it when you see it."

Each guitarist, in turn, eventually gets a chance to shine, and for 60 seconds, can become Eddie Van Halen or Jimmy Page or Brian May.

Air guitar is growing in popularity (the U.S. competition has steadily grown in size since 2002) and is coming closer to a viable occupation for some. Crane has written a memoir titled "To Air is Human: One Man's Quest to Become the World's Greatest Air Guitarist." Cedric Devitt and Kriston Rucker, the competition's organizers, have produced "Air Guitar Nation," a documentary that has played at various film festivals.

Not everyone is a believer. After a TV segment on air guitarists several years ago, CNN anchor Jack Cafferty declared: "That's the dumbest thing I've ever seen."

It's a familiar gripe to air guitarists.

"It's funny, but it's not a joke," says Dave Roberts, a 26-year-old graduate student from Miami. "It's like circus clowns; they're funny, but they take what they do very seriously."

Psycho Dave (as he calls himself) is one of the most dedicated air guitarists, though his performance of Motorhead's "Ace of Spades" went south when his black wig fell off during his first jump kick. He says he wasn't blessed with the ability to play music, only the ability to love it.

"Every kid who grew up listening to rock music — actually, any form of music — they close their bedroom door, put on their favorite album and pretended they were in their favorite band," he says.

Matthew Schwartz — aka Count Rockula — advanced to the second round thanks to a Michael Jackson-esque performance of Alien Ant Farm's cover of Jackson's "Smooth Criminal."

"Everybody's got a little rock star inside," the 29-year-old from Seattle said backstage before the show.

At the Bowery, which packs in about 600 at capacity, the audience was mostly composed of ardent air-guitar fans (there are even "air groupies") and friends and family of competitors. Perched in the balcony were four judges: "Daily Show" correspondent Jason Jones; former international champ Miri Park; Gavin McInnes, founder of Vice Magazine; and Leigh Lust, an A&R man for Atlantic Records.

"You are all nerds!" Jones displayed on his dry-erase board, meant for scorekeeping.

The various acts can be quite outrageous. Common techniques include stage-diving, shirt-tearing and knee-sliding. It can come close to descending into a male strip show.

Many of the acts were planned spectacles of performance art.

Nordic Thunder, a 22-year-old named Justin Howard, was led on stage in chains by his handlers while an air roadie pulled an imaginary guitar from a real guitar case and proceeded to tune it.

Before performing, all contestants were asked to sign a legal release that included a clause vouching for one's mental health. Howard's performance didn't appear to prompt any concern among the organizers.

"I usually don't remember or can't really think while I'm air-guitaring," said Fatima Hoang, a 26-year-old artist and former ceramics teacher.

Hoang, whose stage name is Rockness Monster, was the 2005 winner. But the defending champ's self-described "Tasmanian Devil" style failed to take the trophy this year.

Mike Torpey, a 23-year-old from Nashua, N.H., who "played" Pink Floyd's "Young Lust," explained that his style was "a little more conservative ... I'm more technical."

Did this mean he really knows how to play?

"No, I don't play guitar, but I've been around guitar my whole life," he answered.

No women made it to this year's contest, but several have in years past. The oldest air guitarist was 43-year-old Scott Gilbert, who traveled from Phoenix with one of his five kids.

Calling himself Mid-life Crisis and describing himself as a metalhead from the '80s, he said air guitar was his "little Everest." Win or lose, he said this would be his last competition — but after a lambasted performance of Van Halen's "Eruption," he stood sweating backstage and declared he'd be back next year.

Instead, the night belonged to Hot Lixx Hulahan, a 32-year-old from Alameda, Calif., named Craig Billmeier.

Billmeier wore a black sombrero and began his routine seated, playing a reserved Spanish acoustic part — though he soon leapt into more frenetic playing.

In the second and final round — when six finalists air-guitar to 60 seconds of the same song — Billmeier took things a step further than the rest. When his turn came, he ran through the crowd, up the stairs to the balcony and gyrated directly in front of the judges as plastic cups of beer flew in every direction.

His win, though, was disputed. The hometown hero from New York, Andrew Litz (stage name: William Ocean) was considered the winner by most, largely because of a stage dive where he crushed a beer can with his back. He also had "A-I-R" shaved into his chest hair.

After the judges and organizers briefly considered an "air-off" between the Billmeier and Litz, order was restored and Billmeier, whose combined score from both rounds beat Litz, was declared the U.S. champ.

He pledged to "slay" all comers in Finland.

As an encore, everyone in attendance was invited on stage to air-guitar to Neil Young's "Rockin' in the Free World." Nearly 40 people bunched together, individually doing their best Young impression, each living out a small piece of rock 'n' roll dreams.