The number of online adults who have used online classified ads has more than doubled in the past four years. Almost half (49%) of internet users say they have ever used online classified sites, compared with 22% of online adults who had done so in 2005. On any given day about a tenth of internet users (9%) visit online classified sites, up from 4% in 2005.
http://www.pewinternet.org/Reports/2009/7--Online-Classifieds.aspx
