At Circular Quay, on Sydney's harborfront, among tourists in goofy head gear and Christians handing out copies of the New Testament, a group of pinheads have set up a makeshift badge bazaar around a huge Moreton Bay Fig tree. The scale might be small, but the vibe is pure Wall Street. The pin game is all about smart networking and sharp dealing, snaring the trophies you want by trading your duplicates rather than forking out cash. Dedicated pinheads have been known to loiter in the lobbies of five-star hotels at check-out time, hoping to talk corporate Games visitors into parting with their "guest pins" before they head to the airport-where other pinheads may be lying in wait. And the game is getting bigger: during the Atlanta Olympics, an estimated 3 million pins changed hands.

Like all passionate collectors, pinheads are obsessed. And, they say, misunderstood. Leonard Braun, 65, wears a Barcelona T-shirt and an exoskeleton of pins, including a badge of honor that reads pinologist. His wife reckons he's juvenile. "She doesn't understand it, and that's a fundamental problem," says the retired physicist from Los Angeles. "But it's probably better than collecting race cars or women." Still, the absurdity of his passion hasn't escaped him: "At times I've had an out-of-body experience: I've seen this grown man trading pins on the ground like a kid, and thought, I'm much too serious for anything so trivial." And yet he keeps coming back to score more Olympic pins, the collectibles that started as cardboard identity discs at the first modern Games, in Athens in 1896. For Braun, collecting is a way to make friends, a hobby that crosses social and cultural boundaries. In 1988, on the streets of Seoul, he says, he traded with Prince Albert of Monaco.

Under a freeway overpass at Darling Harbour, more than 50 people from all over the world have congregated under a white tarpaulin to talk pins and do deals. For many, this is a biennial reunion: they turn up at every summer and winter Games. It's also where their version of the competitive Olympic spirit kicks in. Bud Kling, a 53-year-old tennis coach from Pacific Palisades, Calif., has been to six Games and has more than 20,000 pins, which cover his office walls and sparkle in custom-made display cabinets. A fellow trader comes up to gloat, having snapped up a sought-after NBC guest pin. "So what did you have to give up?" asks Kling. "If I told you, you'd die," his friend replies with a self-satisfied grin. "They took a UPS [corporate pin]." There's a pause as Kling shakes his head. "Jesus," he says, visibly impressed. The day before, Kling had finally got his hands on a World Olympic Congress pin he'd been chasing for more than two years. "It's the sense of achievement," he says. "And it's a lot easier than putting a moose head on my wall."

At a nearby table, Al Falcao, from Toronto, holds court. He's something of a celebrity in the pin-trading scene-a king pin, if you will. "You need a bit of savvy," he explains. Falcao has come a long way since he stuck his first seven pins into a pizza box after the Calgary winter Olympics in 1988. That's when he decided to branch out from stamps, license plates and baseball caps. His priorities are, in descending order: guest, media, national, and limited-edition corporate-sponsor pins. He claims his collection stands at 25,000. "I've given out 5,000 pins in exchange for a smile," he says. Falcao prides himself on his diplomacy and his knack for sealing a deal. A man approaches him and offers a Korean delegation pin, but the one he wants Falcao to give him in return-an IBM-laptop pin-is far more valuable. "This is a $30 pin!" Falcao tells the man. "Touch it. Feel it." The man walks away; Falcao is irked. "I will never forget that guy's face. That will bother me until I get it-and I will get it," he says.

Such are the disappointments of this, the Olympics' biggest unofficial sport. But win, lose or draw, at least Falcao and his pinhead friends can console themselves with the prospect of a few thousand more tiny medals.