YNOT – Search.xxx, a search engine devoted to sites in the .xxx domain space, launched Wednesday. Marketed as “the search engine for porn,” the directory includes some 21 million pages of adult content, according to Stuart Lawley, chief executive for dot-xxx overseer ICM Registry.

ICM owns and operates the search engine, which works like any other online mega-directory, except Search.xxx’s spiders crawl and index only pages with the .xxx extension. How the rankings are determined is a bit mysterious, since simply residing on [SearchTerm].xxx appears to be insufficient to guarantee a top spot in the listings. For example, Gay.xxx appears first among the results for the search term “gay,” but Amateur.xxx doesn’t appear within the first five pages of results for the term “amateur.” The latter may owe its low profile within the results to a redirect script that automatically shuttles users to NudeTube.com.

Search.xxx looks and functions, at least for end-users, much like a simplified version of Google with a couple of extra bells and whistles. No obvious paid advertising appears on the results pages, but a hierarchical list of subcategories related to the present search appears in a navigation menu on the left-hand side of each page. End-users can manipulate the engine’s skin and language, as well as segregate results by sexual orientation (straight, gay and “all”).

According to Lawley, the official search engine of .xxx offers users a streamlined search experience while protecting them from malware and guarding their privacy. He also said Search.xxx is more likely to lead users to exactly what they seek than, for example, Google, which recently changed its algorithm in a way that shoves many adult sites off the first page of results in favor of pages bearing definitions of terms or articles about health or sexuality.

The search engine’s launch represents ICM making good on a promise it made to .xxx registrants when the domain space debuted about nine months ago. Since then, about 240,000 .xxx domains have been registered, approximately 80,000 of them defensively, Lawley told IDG News Service. The figure is almost double the 125,000 domains ICM predicted it would register within five years after launch.

Lawley also told IDG he and ICM plan to introduce a micropayment service early next year. The service will employ an iTunes-like model, allowing consumers to purchase video clips from participating .xxx sites for less than $2 apiece.