A new market for writing has arisen online--writing to please search engines instead of people. Content optimized for successful search results ranges from informative articles to incoherent copy stuffed with keywords, an annoyance that's being labeled "search-engine spam."

Articles with popular keywords can generate significant traffic for Web sites, giving site owners a financial incentive to host content that will rank near the top of search results. A cottage industry has formed to help people do it. ArticleBot, for instance, advertises software that, for $30 a month, rewrites copy by substituting synonyms for certain words so that text can be repurposed to score well on search engines. Hot Nacho Inc. is testing software, called ArticleWriter, that gauges whether online content will appeal to search engines. "It's basically a text editor that gives an analysis as the article is being written of whether the article looks 'on topic' to a search engine," owner Chad Jones says.

Google Inc.'s Webmaster Guidelines warn against crafting copy for its search engine: "Make pages for users, not for search engines," it reads. Search engines don't hesitate to remove from their rankings sites violating the policy. But that hasn't stopped many from trying.

Blogger Andrew Baio last week on his Waxy.org site questioned the purpose of thousands of articles on WordPress.org, a blogging software site, and whether they were "designed specifically to game" Google. Google and Yahoo removed the pages from their respective indexes. The content in question came from HotNacho.com, and WordPress.org was hosting it in exchange for a fee, Jones says. He says the content was testing Hot Nacho's ArticleWriter software. WordPress couldn't be reached for comment.

Just as legitimate E-mail marketers feel the backlash against spammers, well-intentioned search-engine marketers may suffer if tricksters persist. Says Chris Winfield, president and co-founder of search-engine marketing company 10e20 LLC, "One of the most important things for any search engine is people having confidence and becoming repeat users."