Google has launched Google Custom Search Engine, which allows publishers and other users to build their own, customized vertical search engine for their sites - and earn a share of ad revenue.

With Google Custom Search Engine, bloggers and other publishers can create Google search indexes consisting only of sites they select, reports Search Engine Journal. Publishers will share in revenues generated from Google AdSense search ads. Educational institutions, nonprofits and government organizations can choose not to run ads on their search results.

Google VP of Search Products Marissa Mayer termed Google Custom Search "the most significant launch that Google would announce in the final months of this year."

The customizable search engine is Google's attempt at tapping "the wisdom of the crowds," something rivals Yahoo and startups such as Rollyo.com and Eurekster.com have already been focusing on, points out Reuters.

How the Custom Search Engine works, according to Google: "organizations or individuals simply…select the websites or pages they'd like to include in their search index. Users can choose to restrict their search results to include only those pages and sites, or they can give those pages and sites higher priority and ranking within the larger Google index for their site. Users can then customize the look, feel and functionality of their search engine."

Google provides examples of sites using Google Custom Search Engine.

Google also offers a collaboration feature. Publishers can let other people whose expertise they trust to contribute to the publisher's Custom Search Engine, either by inviting people or allowing anyone to volunteer to collaborate, with the publisher's approval.