While few objects rival torches in covetability, medals certainly come close. Victors' medals sell for thousands of dollars; in 2006, O'Neil sold a gold from the St. Louis games for $49,000. Even certain participation medals can go as high as $20,000 if they are from those same St. Louis games. Rarity is a key factor: In 1904, only 651 athletes participated in the games; this year, nearly 11,000 athletes will compete.

Provenance does sometimes come into play; clothing worn by winners, for example, is extremely popular. In June 2007, Sotheby's auctioned off seven jerseys belonging to players on America's 1992 basketball "Dream Team" for $10,800. Imbued with history—the team, which included Charles Barkley and Magic Johnson, was the first to appear after a rule change allowed professionals to play in the Olympics—as well as sweat, the uniforms represent the ultimate acquisition for collectors. Items with a specific, compelling story top a specific year or city, Allen says. As with any Olympic collectible, "much of the value has to do with the performance that the athlete or team had."

The big names don't come up all that often, though. "Dorothy Hamill and Mark Spitz have no financial need to sell their stuff," Allen points out. But celebrities do donate items to fundraisers, and those things can trickle into the marketplace. Down-on-their-luck stars also sell their wares. A few years ago, Mastro auctioned Mike Tyson's boxing trunks and robe from his (failed) 1984 Olympics tryout for more than $10,000, and skater Tonya Harding made headlines when word got out that she was unloading her closet of costumes in the mid-1990s. An eBay seller is currently auctioning one of her (non-Olympic) outfits for $5,000.

It's too soon to tell which athletes' belongings will have legs this year, and experts certainly don't put much stock in the heaps of official goods. "They'll make great mementos, but they won't appreciate," says Allen of the record 300 products Beijing has licensed to help offset its (also record) $40 billion in infrastructure and organizational costs. Indeed, thousands of Olympic pins, stamps, postcards, and Coca-Cola cans are available on eBay—from games past and present—for less than $20. And while ticket stubs from the storied 1980 "Miracle on Ice" U.S. versus Soviet Union hockey game can fetch $500, game ephemera, too, is best tucked away with your photo albums.

A smarter strategy: Keep your eyes peeled for material from the 1908 or 1948 London Olympics. As the 2012 games near, prices are sure to jump.