Here are some numbers that YellowPages.com published in early 2008:

• The Yellowpages.com Extended Distribution Network for paid advertising includes: YellowPages.com, AOL Yellow Pages, Yahoo Yellow Pages, AreaGuides.net, Yahoo! Local, 411.com and AnyWho.com. 
• Together these sites make up the 35th top web property as measured by comScore and claim 35.8 million unique visitors in January 2008.
• YellowPages.com, by itself, attracted 19,401 unique visitors in that same month, which was about the same as Yahoo! Local and Yahoo! Yellow Pages combined.