WhitePages.com has between 16 and 20 million uniques depending on the third party service you consult. The site dominates “people search” and the business is something of a cash cow. Right now the company partners with others for business (yellow pages) search. Apparently, I was told, each year the company puts its local search traffic up for competitive bidding. I was unaware of this.
Here’s an example search result (“sushi, Boston, MA”) that goes to a Superpages.com page:
This same individual also told me that the company is quietly seeking additional vertical bidders for specific categories rather than outsourcing to one or two providers for all headings as it has done in the past.
WhitePages could buy a database and do local business search itself, but I suppose it finds this approach more lucrative.