Petside.com, a site for pet owners run by NBC Universal (NYSE: GE) and Procter & Gamble, could represent a new way for major media companies and marketers to do business on the web, a NYT story suggests.

The site already features P&G products like IAM’s pet food, and it will benefit from a tie-ins to a pet-focused channel on NBCU’s iVillage and a weekly spot on the network’s Today Show. But since both NBCU and P&G share the ad revenue from PetSide, the site is not just a branded vehicle for P&G products. The two companies have opened the site up to general marketers, such as Banc of America and LasikPlus Vision Centers. And it will also begin selling ad space on PetSide to P&G’s competition. By not defining PetSide strictly as a P&G venue, the company believes it can draw a greater audience and ultimately give its own advertising on the site more impact.

Most pet sites don’t have particularly large amount of visitors - PetSmart.com had the most visitors in the pet category last month, reaching 2.48 million uniques in October, according to Nielsen Online - but NBCU and P&G are undaunted. They believe PetSide, by aggregating material from other sites - as well as syndicating PetSide’s own videos and original content to others - will be able to draw audiences from the various pet-centric sites and related social nets already out there. And NBC, aside from handling PetSide’s ad sales, has used to the site as a jumping off point to start a “pet ad network” for others like WorldwideFido.com and DogCentral.com. More details about NBCU’s partnership with P&G in this release.