A service from Yahoo offers web publishers the chance to design a search-engine tailored to the focus of their site or blog.

Yahoo Search Builder lets publishers hand-pick the websites they want included in their search engine's index, the Sunnyvale, California, company announced yesterday.

If publishers don't want to assemble the index manually, they can also tune the main Yahoo search engine to focus on the topic of their choice.

Yahoo expects the service will appeal to publishers that want to attract visitors by offering specialised search engines that limit results to a specific area. For example, the publisher of a cricket blog could build a search engine that returns results only from sites devoted to the sport.

Yahoo will provide publishers with statistics about their search engine, such as the most popular queries and the overall usage level.

The move extends Yahoo's efforts in the area known as social search, which many consider the next major evolution of search-engine technology. People are at the center of social search sites, not the mathematical algorithms and automated web crawlers that have powered search engines traditionally.

By letting people participate in the discovery, categorisation and sharing of indexed websites, social search sites attempt to deliver search results that are more relevant and targeted.

More information about Yahoo Search Builder can be found here.