http://www.forbes.com/2001/05/25/0524porn.html
Its rival research outfit, Net Ratings, tracks the number of visitors to porn Web sites. It says that in April 2001, there were 22.9 million unique visitors to porn sites. This says nothing about how long each visitor stayed or whether they spent a dime. In any event, the number of visitors is less than the number who visited news sites (41.1 million), finance sites (34.2 million) or greeting card sites (25.5 million). When was the last time you heard anyone talk about how greeting card sites dominate the Net?