The Web largely remains a place to have fun and enjoy personal pursuits. The Pew Internet and American Life Project estimates that 70 million U.S. adults are online on a given day. Activities formerly done offline, such as checking the news and weather, are now done online by nearly twice as many people as in 2000. The market for paid content continues to expand, with sites collecting $1.8 billion in revenue in 2004. Dating sites account for more revenue than any other type of site. Entertainment sites, such as music- and movie-downloading destinations, rank second despite 90 percent revenue growth in 2004.

But these market figures exclude two significant sources of online revenue: pornography and gambling sites. While the nature of the sites' content makes accurate estimates of their traffic and revenues difficult, Nielsen/NetRatings monitored site visits among a panel of surfers and found that during April alone, 24 percent visited porn sites and 18 percent visited gambling sites. It's no wonder, then, that there are an estimated two million pornographic sites on the Web today and that the online gambling market is expected to hit $24 billion by 2010.