Wallet Bingo

Everybody knows it takes money to make money. Now, an Israeli group has a scheme called BillGame that pushes that notion to the extreme. The game is played by scribbling a Web address on everyday currency that, its backers hope, will drive traffic to their Web site as the bills worm their way around the globe.

A wacky idea? You bet, but rival wheresgeorge.com tracks more than 3 million U.S. bills just for fun. And BillGame lets you win cash. To play, just pull the cash out of your wallet and enter the serial numbers on the game's Web site. Then write www.billgame.com on the bills. When someone gets your money and reenters the serial number on the BillGame site, you both earn points that add up to cash prizes. The backers say they'll make their money selling ads on the site. They might want to move fast: If digital cash ever replaces the real thing, BillGame will be less profitable than Liar's Poker.

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