Frito-Lay is tapping a new “agency” to create the ad spot for their $2 million Super Bowl ad spot — consumers:

Do-it-yourself ads will move from Web promotions to the biggest stage in advertising with the airing of the first homemade commercial in a Super Bowl.

Frito-Lay on Thursday will invite consumers to enter their own 30-second ads for Doritos in an online competition, with the winner broadcast during the Feb. 4 NFL championship on CBS.

The consumer ad will vie for viewer attention with some of the fanciest professional commercials. Marketers lavish huge budgets on Super Bowl ads after spending millions to buy time because the game remains the most-watched TV program.

Doritos marketers will choose five finalists and the makers of the top five all will get a trip to the Super Bowl. Online consumer voting in January will help pick the winner — which will not be announced before it airs unedited during the game.

So finalists get a free trip to the Super Bowl, and the winner gets the deep personal satisfaction of seeing their ad on the Super Bowl — which could of course lead to a financial return from actual paid creative work.

But you have to wonder whether the winner of the Frito-Lay ad contest would prefer receiving the millions of dollars in creative agency fees that Frito-Lay otherwise would have paid.

It’s one thing to leverage the previously untapped pool of brand enthusiasts who might be capable of producing ads that are as good as or better than those produced by “professional” marketers. It’s quite another to try to take advantage of consumers’ willingness to do this work for free.

You have to wonder how long this willingness will last.