Online classifieds are booming, according to a Pew Internet & American Life Project and comScore study, which found that traffic to classifieds sites is up 80 percent year over year (September to September). Registering the greatest growth was Craigslist, up 156 percent, in first place with the most unique visitors as of September: 8.76 million. In second place was Trader Publishing Company, which grew 90 percent, reaching 8.18 million unique visitors.