(FORTUNE Magazine) – If you had seen Kelly Murphy hawking T-shirts and handing out free pizza in front of shiny new Chevrolet Blazers one day last spring at Auburn University in Auburn, Ala., you might have thought she was working for the local Chevrolet dealership. In a way, you'd be right. But instead of getting paid to promote cars, Murphy, then a senior, got college credit.

Corporate marketers are always looking for ways to sell to college trendsetters. But many universities restrict corporate advertising on campus. So companies look for roundabout entry points. They jockey for exclusive soda contracts in dining halls or sponsor the group-of-the-moment's concert in the freshman quad. But EdVenture Partners, based in Berkeley, had a particularly innovative--some might say sneaky--idea. It arranges for students to earn credit marketing products for General Motors, Coca-Cola, Clairol, E*Trade, and Time magazine (owned by FORTUNE's publisher) at some 300 universities and high schools across the country.

EdVenture pockets a $12,500 to $17,500 fee from companies for making introductions. So now, for example, Wells Fargo sponsors a marketing seminar at Colorado State University, and GMC Trucks foots the bill for an applied advertising class at Diablo Valley College in Pleasant Hill, Calif. At Auburn University, Murphy and her marketing classmates earned credit by throwing a campus carnival to showcase Chevrolet cars. Her class got $2,500 from the local Chevy dealer to pay for their marketing plan. The dealer also made a $500 contribution to the marketing department. "For the semester I had a job--to promote GM and its cars," says Murphy. "It was a lot better than taking notes."

The word-of-mouth buzz generated by student-run promotions is considerable. After one event sponsored by a local Pontiac dealer at Kennesaw State University in Georgia, students who said they would consider buying a Pontiac increased by 32%. "There's no better way to reach this market than through their peers," says Tim Hudgens, Southeast marketing manager for Pontiac-GMC. "You just don't get the same results from a TV commercial, newspaper campaign, or even an ad in FORTUNE."

That's just what troubles critics. EdVenture calls its classes educational projects and participating students and professors view them as precious hands-on experience. But critics say they are a way to circumvent rules against corporate advertising on campuses. Says Gary Ruskin, president of Commercial Alert, a consumer watchdog group that campaigns against any type of corporate presence on campus: "Increasingly schools are turning into cash-and-carry operations for the advertisers and marketers of America." Grade: A for marketers, C for educators.