Wikia Search, the open-source search engine that is the brainchild of Wikipedia founder Jimmy Wales, will begin letting anyone participate in building its index by adding, deleting and rating Web pages. "This is a complete overhaul of everything," said Wales.

During its "alpha" period, which started in January, Wikia Search has drawn about 20,000 registered users who have in turn made about 60,000 edits to search results and written about 25,000 mini articles.

However, starting on Tuesday, anyone, registered or not, will be able to influence what the index contains, as well as rate the quality of its Web pages, Wales said.

In addition, people will be able to edit the content of a search result URL by modifying its headline and description. Moreover, people will be able to capture a portion of an indexed Web page, such as some text, and add it directly back to the Wikia Search index, a feature Wales calls "annotation."

Contributions are reflected immediately and don't go through an approval process. The quality control will be primarily up to the search engine's user community, Wales said. In cases of attempts to spam the index on a large scale, it's possible to mass delete those submissions and block specific users, he said.

"It's all the classic things that we learned from the wiki model: basically putting all that editorial control into the hands of the community so that it's easier to do good than to do harm. That's the basic philosophy," he said.

Wales, however, acknowledged that Search Wikia is "pretty out there in terms of openness" but is confident that, far from leading to chaos, the broad participation of users will boost significantly the engine's index, which now contains about 30 million links, a relatively small number. "We wanted to let the community decide how to grow the index," Wales said.

Industry analyst Greg Sterling of Sterling Market Intelligence calls Wikia Search's approach "very interesting," but points out that the benefits of its human-powered approach will take years to materialize.

An open question is whether enough volunteers will participate, so that the index reaches the necessary size and is updated frequently enough, Sterling said.

In this sense, categories like news articles, blog postings and product listings will be a particular challenge because they are so timely and generated with such speed and frequency, he said.

In addition, as is the case with wiki-based products, there will be the question of whether the volunteers are trustworthy and how reliable their judgment and decisions are, Sterling said.