First up is Yellowpages.com, which averages 100 million monthly searches. Basic listings (for stores with physical locations) are free, and the company also offers "YPclicks!" which allows business owners to buy PPC ads on a monthly basis.
Meanwhile, Superpages.com also offers free basic listings, in addition to PPC and pay-per-call options. The IYP service also will create simple Web sites as part of a package.