Madison Avenue has always tried to create infectious ads. Think of those beer commercials with catch phrases that some of your more tiresome coworkers repeat around the water cooler. But viral marketing truly came of age with the Internet.

Marketers discovered that if they came up with a really good beer ad, consumers would e-mail it to their friends. That was a revolution at the time. Now it seems so Web 1.0. In the age of user-generated content sites like YouTube, MySpace Video, and Google (Charts) Video, consumers and advertisers are able to upload ads that can be shared virally by millions of people.

This means some interesting twists for the business of advertising. A successful viral ad is distributed widely for free - Smirnoff didn't pay YouTube a dime. On the other hand, the advertiser has no control over where the message winds up. (There's always the chance that it might appear next to a Hitler video or a booty clip.)

And here's an intriguing question: Can YouTube and Google Video figure out a way to make this a business? If so, could they become the web's equivalent of the broadcast networks?

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