[shibumi]

"Offer to sell positive reviews to businesses profiled on Yelp.com (presuming that you actually have a legitimate experience with them)"

Or, you could extort businesses by threatening them with not giving negative reviews if they don't pay you large sums of money.

(It's a variation on the Doug and Dinsdale Piranha Business Model.)

[peyton randolph]

Really? Are you trying to get them in trouble with the FTC? Compensated endorsements must be clearly disclosed. The failure to do so is considered a deceptive trade practice.