Some of the biggest search companies, including Yahoo Inc., are also putting money behind programs some consumers can't stand. Yahoo's Overture ad division, recently renamed Yahoo Search Marketing, has a long-standing relationship with Claria Corp., an ad- supported company that installs pop-up ad software. Yahoo places copies of its clients' ads on Claria, splitting revenue that results from that business. In a withdrawn filing for a public stock sale last year, Claria said the arrangement brought in 31% of its $90 million in 2003 revenue.

Goldman Sachs last week estimated that Yahoo took in $20 million annually from Claria and Intermix Media Inc., an adware company recently sued by New York Atty. Gen. Eliot Spitzer. A Yahoo spokeswoman said Claria met the company's standards for informing users what it was doing.

Claria competitor 180Solutions makes pop-up software that is installed automatically through browser security holes. Although the firm said it was cracking down on that practice, it still offers bounties for each installation, a model that analyst [Gary Stein] said encourages "all kinds of sneaky tactics." Recent 180Solutions ads ran on behalf of J.P. Morgan Chase and Disney.