Popularity contests increasingly decide what people see on the Web.

Features like most-viewed, most-popular and most-emailed lists democratize news and information, advocates say, letting consumers play a role in what's deemed worthy of others' attention, taking it out of the hands of an unseen editorial elite. Now, though, a diverse group of actors -- ranging from spyware makers to a venture-backed start-up -- is helping push specific videos, articles and photos to the top of those lists. Some of the Web sites targeted now are having to grapple with how to draw the line between user input and unacceptable manipulation.

News media and other Web sites traditionally have relied on editors to select which content to display on their home pages and feature prominently to users. But lately, many sites are basing such selections at least partly on how popular a given piece of content is with users. Google Inc.'s YouTube video-sharing site lists the video clips that have been viewed the most times, or are the highest-rated by users. Digg Inc., a community Web site that is the archetype for the popularity-contest model, relies on voting by users to help select which Web page links to feature in the lists for various media and subject areas that make up its site.

Spyware makers and others have taken notice, building software that tries to boost the prominence of specific items on some sites, by automatically clicking on them repeatedly or tricking unsuspecting users into doing so. The rewards for such tactics: the items are prominently featured on the "most viewed" and "highest rated" pages of sites, generating more exposure. "It's paramount for sites that are publicly driven to think about this every day, this arms race against the manipulators, " says Jay Adelson, chief executive of Digg, which is based in San Francisco.

The latest to try to capitalize on the popularity-contest trend is start-up Collactive Inc., which lets individuals create bulletins about specific online content that they can then blast out to other people. Users can identify items such as articles or video clips from a number of different sites, and specify what actions -- such as emailing articles and giving videos a specific rating on YouTube's five-star scale -- that they want Collactive to direct other people to take. The users can then email a link to the Collactive bulletin to friends or post it on their Web sites. Collactive, a Delaware-registered company that operates mainly out of Israel, then automatically walks the recipients through the process of viewing and emailing or rating the content. While the service is free for individuals, the company plans to charge businesses, politicians and some nonprofits for usage.