Now some of the early entrants into the Net porn industry, flush with financial success, are buying competing sites. This makes it more difficult than ever for new Webmasters to make business connections. Lee Noga of content distributor ZMaster predicts the shakeout will continue: ``We're already seeing people buying other sites just for power. Ten years from now, there might only be ten humongous adult companies, but they'll own about 100,000 sites each.''

Up to 30 million individuals a day log on to adult Web sites. After running a search at a portal site or adult index, the next stop is probably a site with free images.

According to Rick Muenyong of The YNOT Adult Network, free sites comprise 70 and 80 per cent of the adult material out there. These sites are usedas ``bait'' for pay sites and make their money by successfully guiding viewers to premium services on other sites.

Conventional online companies can still get away with charging advertisers for the number of banner ads shown to viewers. In sharp contrast, free porn sites make money only when a user visits an advertiser's site and makes a purchase.

Typically, a premium site shares 30-60 per cent of each sale with the referring site. This may seem generous, but it's actually very difficult for free sites to capitalise on these arrangements. Although 5-10 per cent of visitors might click an ad (known as click through), only one or two out of every thousand will actually purchase the services advertised (known as conversion).

In order to survive, free sites will use almost any trick to raise click through rates: false promises of more free content and multiple pop-up ads that appear when a viewer tries to leave are the most annoying recent trends. By and large, viewers don't seem to mind the tricks, as longas there's enough free content to satisfy them.

As mainstream advertisers begin to charge by clickthrough and conversion, look for these tactics to make their way over to the mainstream Web.In order to make any money referring customers to pay sites, free sites themselves must attract thousands of users. So far, index sites with thousands of links, such as Persian Kitty's Adult Links, have had the best luck grabbing traffic and making money.

With this lesson in mind, Webmasters aggressively pursue cross-linking agreements. Top ten (or fifty, or three hundred) lists, which rank ``partner'' sites based on overall traffic, were trendy in 1997, but partners often artificially inflate hit counts through endless circles of links within their sites. SexTracker, a more sophisticated service that tracks traffic throughout the entire adult industry, is perhaps the ultimate outgrowth of the list trend: its 12,000 adult-site rankings are a frequent starting point for porn-hungry surfers.

Some pay sites have stoopedto shady business practices. Many services make it difficult to cancel memberships, hiding ``cancel'' buttons or changing phone numbers without warning. Some promise one free month of access--but then secretly charge for the first month before allowing customers a free second month. One insider even said that he shared its credit card database with other Webmasters who fraudulently charged the cardholders for services that were neither ordered nor delivered. When the cardholders began filing fraud claims with their credit card companies, the other sites declared bankruptcy and split with the loot.