The brisk sales activity on Ashe's site flies directly in the face of what everyone knows about Internet commerce. This was supposed to be the year the Web became a gigantic digital department store, an electronic emporium that would enable consumers to purchase all manner of traditional goods and services. But amid all the commercial promise of the Internet, there has been one troubling reality: Consumers are not putting their money where their modems are--and they're spending less than expected. As industry analysts and executives retool their spreadsheets, wondering where, when and how money will be made on the Web, there is a rush of commercial activity in the area of X-rated, adult content. "People in the research field have been reticent to touch this topic," observes Scott Smith, a Web commerce analyst with Jupiter Communications, "but there is plenty of money being made there."

Indeed, about one fifth of the Web audience--which is 60 percent male-- says it regularly seeks out adult material online. The Web also boasts more than 600 merchant sites where consenting adults can purchase legal forms of pornography. And this year, adult entertainment on the Internet is expected to generate revenues of $51.5 million, the third-largest sector of sales, surpassed only by computer products and travel. The trend isn't surprising. In recent years, sex has been linked to the early adoption of many nascent communications technologies. Initial sales of videocassette recorders, home videos and subscriptions to cable television, for example, were all boosted by consumers who wished to view pornography in the privacy of their homes. The Web has proven no exception. "Human behavior isn't altered by this technology," insists Paul Callahan, an analyst with Forrester Research. "This sort of thing is expected."

Profits. An overwhelming percentage of Web surfers clearly are not interested in digital smut, but in a perverse sense, sex sites like Ashe's may provide the rest of the Web's merchant community with a few important pointers on how to make money.

Apart from technology concerns, selling on the Web is particularly troublesome for many cybermerchants. Some commercial sites, for instance, encounter snags when they ask seemingly loyal customers to pay for content. Take the cautionary tale of Web Review, a popular general-interest news and information site that boasted daily readers numbering in the hundreds of thousands. Last spring, the site asked readers to pay for subscriptions. There were few takers, and, in May, the Web effort went under. Analysts believe that a number of publications seeking profits on the Web could eventually go the way of Web Review. With many Web sites--including the Wall Street Journal's--now trying to convert visitors into paying online subscribers, Playboy Interactive may offer some solid commercial guidance. Later this month, Playboy magazine's site, the 11th-most-visited place on the Web, will test a two-tier subscription model for customers who wish to delve into the publication's vast archives. Playboy will allow users to enter the site and access large amounts of free material, but it will cordon off a special area for paying subscribers.

Online sex also has had an effect on other high-tech markets, ushering in companies that create blocking software and a host of enterprises that authorize digital ID cards. For a monthly or annual fee, these firms verify a Web surfer's age, then issue an identification number that the customer must type in before entering sites that are closed off to underage users.

Sex is popular on the Web today, but its hot sales could be a fading phenomenon. As the Internet diversifies, with more business-to-business transactions and a growing number of women and senior-citizen users, the mix of goods and services will change. Already, there are signs that women are having an effect on the types of sites being accessed. Between January and May of this year, the portion of female users on the Web jumped from 32 percent to nearly 40 percent. At the same time, the share of Web surfers who said they accessed adult material dropped from more than 1 in 4 to just over 1 in 5. This trend is expected to continue in coming years, and that's a relief to those worried about the Web becoming an electronic massage parlor.